Method, device, and system for downlink data reception and harq-ack transmission in wireless communication system

ABSTRACT

The present invention relates to a method, device, and system for downlink data reception and HARQ-ACK transmission in a wireless communication system. According to the present invention, in the method, device, and system for downlink data reception and HARQ-ACK transmission, a first physical downlink control channel (PDCCH) for scheduling of a first physical downlink shared channel (PDSCH) is received, and a second PDCCH for scheduling of a second PDSCH is received. Thereafter, uplink control information (UCI) including a hybrid automatic repeat request (HARQ)-acknowledge (ACK) codebook for the first PDSCH and the second PDSCH is transmitted to a base station.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system, andmore particularly, the present disclosure relates to transmission ofdownlink data and transmission of an acknowledgment thereto in awireless communication system.

BACKGROUND ART

3GPP LTE(-A) defines uplink/downlink physical channels to transmitphysical layer signals. For example, a physical uplink shared channel(PUSCH) that is a physical channel for transmitting data through anuplink, a physical uplink control channel (PUCCH) for transmitting acontrol signal, a physical random access channel (PRACH), and the likeare defined, and there are a physical downlink shared channel (PDSCH)for transmitting data to a downlink as well as a physical control formatindicator channel (PCFICH) for transmitting L1/L2 control signals, aphysical downlink control channel (PDCCH), a physical hybrid ARQindicator channel (PHICH), and the like.

The downlink control channels (PDCCH/EPDCCH) among the above channelsare channels for a base station to transmit uplink/downlink schedulingallocation control information, uplink transmit power controlinformation, and other control information to one or more userequipments. Since resources available for PDCCH that can be transmittedby a base station at one time are limited, different resources cannot beallocated to each user equipment, and control information should betransmitted to an arbitrary user equipment by sharing resources. Forexample, in 3GPP LTE(-A), four resource elements (REs) may be grouped toform a resource element group (REG), nine control channel elements(CCEs) may be generated, resources capable of combining and sending oneor more CCEs may be notified to a user equipment, and multiple userequipments may share and use CCEs. Here, the number of combined CCEs isreferred to as a CCE combination level, and a resource to which CCE isallocated according to a possible CCE combination level is referred toas a search space. The search space may include a common search spacedefined for each base station and a terminal-specific or UE-specificsearch space defined for each user equipment. A user equipment performsdecoding for the number of cases of all possible CCE combinations in thesearch space, and may recognize whether the user equipment belongs to aPDCCH through a user equipment (UE) identifier included in the PDCCH.Therefore, such an operation of a user equipment requires a long timefor decoding a PDCCH and unavoidably causes a large amount of energyconsumption.

Efforts are being made to develop an improved 5G communication system orpre-5G communication system to satisfy wireless data traffic demand thatis increasing after the commercialization of a 4G communication system.For this reason, a 5G communication system or pre-5G communicationsystem is referred to as a beyond 4G network communication system orpost-LTE system. It is considered to implement a 5G communication systemin an ultrahigh frequency (mmWave) band (e.g., 60-GHz band) to achieve ahigh data transfer rate. To reduce a radio propagation path loss andincrease a transfer distance of radio waves in an ultrahigh frequencyband, beamforming, massive MIMO, full dimensional MIMO (FD-MIMO), arrayantenna, analog beamforming, and large scale antenna technologies arediscussed in the field of a 5G communication system. Furthermore, toimprove a network of a system, technologies such as advanced small cell,cloud radio access network (cloud RAN), ultra-dense network,device-to-device communication (D2D), wireless backhaul, moving network,cooperative communication, Coordinated Multi-Points (CoMP), interferencecancellation, and the like are developed in the field of a 5Gcommunication system. In addition, hybrid FSK and QAM modulation (FQAM)and sliding window superposition coding (SWSC), which are advancedcoding modulation (ACM) schemes, and filter bank multi carrier (FBMC),nonorthogonal multiple access (NOMA), and sparse code multiple access(SCMA), which are advanced access technologies, are developed in thefield of a 5G system.

Meanwhile, in a human-centric connection network where humans generateand consume information, the Internet has evolved into the Internet ofThings (IoT) network, which exchanges information among distributedcomponents such as objects. Internet of Everything (IoE) technology,which combines IoT technology with big data processing technologythrough connection with cloud servers, is also emerging. In order toimplement IoT, technology elements such as sensing technology,wired/wireless communication and network infrastructure, serviceinterface technology, and security technology are required, so that inrecent years, technologies such as sensor network, machine to machine(M2M), and machine type communication (MTC) have been studied forconnection between objects. In the IoT environment, an intelligentinternet technology (IT) service that collects and analyzes datagenerated from connected objects to create new value in human life canbe provided. Through the fusion and mixture of existing informationtechnology (IT) and various industries, IoT can be applied to fieldssuch as smart home, smart building, smart city, smart car or connectedcar, smart grid, healthcare, smart home appliance, and advanced medicalservice.

Here, various attempts are made to apply a 5G communication system to anIoT network. For example, technologies such as sensor network, machineto machine (M2M), and machine type communication (MTC) are implementedwith 5G communication technologies, i.e., beamforming, MIMO, arrayantenna, and the like. Applying a cloud radio access network (cloud RAN)as the above-described big data processing technology may be an exampleof convergence of 5G technology and IoT technology.

In general, a mobile communication system has been developed to providea voice service while securing activity of a user. However, the area ofa mobile communication system is expanding to not only a voice servicebut also a data service, and has been so developed as to provide ahigh-speed data service at the present time. However, in a mobilecommunication system which is currently being used to provide a service,a resource shortage phenomenon occurs and users require higher-speedservices. Thus, a more developed wireless communication system isrequired.

As described above, a future 5G technology requires lower latency ofdata transmission with the advent of new applications such as real-timecontrol and tactile Internet, and a required latency of 5G data isexpected to be decreased to 1 ms. 5G has an objective of providing adata latency that is reduced by about 10 times compared to the priorart. To resolve such problems, a 5G communication system is expected tobe proposed, which uses a mini-slot having a shorter TTI interval (e.g.,0.2 ms) in addition to an existing slot (or subframe).

In the Rel-16 enhanced URLLC (eURLLC), various technologies forproviding a lower latency time and higher reliability are discussed. Toprovide a lower latency time, transmission of an uplink control channelincluding two or more HARQ-ACKs in a single slot is supported. A userequipment is enabled to transmit HARQ-ACK as quickly as possible as aresponse for success of reception of a downlink shared channel, therebysecuring a lower latency time.

DISCLOSURE OF THE INVENTION Technical Problem

The present disclosure relates to a method for designing a semi-staticHARQ-ACK codebook in a 3GPP NR system and a method for transmitting aPUCCH, and an object thereore is to provide a method and a devicetherefor capable of solving a problem occurring in a situation in whichPDSCHs and PUCCHs are repeatedly transmitted in a plurality of slots.

It will be appreciated by persons skilled in the art that the objectsthat can be achieved by the present disclosure are not limited to whathas been particularly described hereinabove and the above and otherobjects that the present disclosure can achieve will be more clearlyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings.

Technical Solution

A user equipment of a wireless communication system according to anembodiment of the present disclosure includes a communication module anda processor that controls the communication module. The processorreceives a first physical downlink control channel (PDCCH) forscheduling of a first physical downlink shared channel (PDSCH), thefirst PDCCH including a first counter downlink assignment indicator(DAI) indicating the number of PDSCHs scheduled up to a serving cell ata time point at which the first PDCCH is monitored and a first total DAIindicating the number of all PDSCHs scheduled in the serving cell untila time point at which a PDCCH is monitored, receives a second PDCCH forscheduling of a second PDSCH, the second PDCCH including a secondcounter DAI and a second total DAI, receives the first PDSCH based onthe first PDCCH, receives the second PDSCH based on the second PDCCH,and transmits, to the base station, uplink control information (UCI)including a hybrid automatic repeat request (HARQ)-acknowledge (ACK)codebook for the first PDSCH and the second PDSCH, a value of the secondcounter DAI being determined based on the number of bits of the firstcounter DAI when the number of bits of the first counter DAI isdifferent from the number of bits of the second counter DAI.

In addition, in the present disclosure, when the number of the bits ofthe first counter DAI is smaller than the number of the bits of thesecond counter DAI, a value indicated by the second counter DAI isdetermined based on at least one of bits with a number equal to thenumber of bits of the first counter DAI among bits of the second counterDAI.

In addition, in the present disclosure, when there are a plurality ofvalues determined by at least one of the bits of the second counter DAIwith the number equal to the number of bits of the first counter DAI, adetermination is made that the value of the second counter DAI is avalue with the smallest difference from the value indicated by the firstcounter DAI among the plurality of values.

In addition, in the present disclosure, when the first counter DAI is 1bit and the second counter DAI is 2 bits, the value of the secondcounter DAI is determined using a least significant bit (LSB) or a mostsignificant bit (MSB) of the 2 bits.

In addition, in the present disclosure, when the 1 bit of the firstcounter DAI is ‘0’, the value of the second counter DAI is determined as‘2’ when the LSB or the MSB of the second counter DAI is ‘0’, and thevalue of the second counter DAI is determined as ‘1’ when the LSB or theMSB of the second counter DAI is ‘1’.

In addition, in the present disclosure, when the 1 bit of the firstcounter DAI is ‘1’, the value of the second counter DAI is determined as‘1’ when the LSB or MSB of the second counter DAI is ‘1’, and the valueof the second counter DAI is determined as ‘2’ when the LSB or MSB ofthe second counter DAI is ‘0’.

In addition, in the present disclosure, when the number of bits of thefirst counter DAI is greater than the number of bits of the secondcounter DAI, the value indicated by the second counter DAI is determinedby extending the number of bits of the second counter DAI to the samenumber of bits as the number of bits of the first counter DAI.

In addition, in the present disclosure, when there are a plurality ofsecond counter DAI values determined by being extended to the samenumber of bits as the number of bits of the first counter DAI, adetermination is made that the value of the second counter DAI is avalue with the smallest difference from the value indicated by the firstcounter DAI among the plurality of values.

In addition, in the present disclosure, when the first counter DAI is 2bits and the second counter DAI is 1 bit, the value of the secondcounter DAI is determined by extending 1 bit to 2 bits.

In addition, in the present disclosure, when the 2 bits of the firstcounter DAI are ‘00’ or ‘01’ and the 1 bit of the second counter DAI is‘0’, the second counter DAI is determined as ‘3’, and when the 2 bits ofthe first counter DAI are ‘10’ or ‘11’ and the 1 bit of the secondcounter DAI is ‘1’, the second counter DAI is determined as ‘1’.

In addition, in the present disclosure, when the 2 bits of the firstcounter DAI are ‘01’ or ‘10’ and the 1 bit of the second counter DAI is‘1’, the second counter DAI is determined as ‘4’, and when the 2 bits ofthe first counter DAI are ‘00’ or ‘11’ and the 1 bit of the secondcounter DAI is ‘1’, the second counter DAI is determined as ‘2’.

In addition, the present disclosure provides a method including:receiving a first physical downlink control channel (PDCCH) forscheduling of a first physical downlink shared channel (PDSCH), thefirst PDCCH including a first counter downlink assignment indicator(DAI) indicating the number of PDSCHs scheduled up to a serving cell ata time point at which the first PDCCH is monitored and a first total DAIindicating the number of all PDSCHs scheduled in the serving cell untila time point at which a PDCCH is monitored; receiving a second PDCCH forscheduling of a second PDSCH, the second PDCCH including a secondcounter DAI and a second total DAI; receiving the first PDSCH based onthe first PDCCH; receiving the second PDSCH based on the second PDCCH;and transmitting, to the base station, uplink control information (UCI)including a hybrid automatic repeat request (HARQ)-acknowledge (ACK)codebook for the first PDSCH and the second PDSCH, in which a value ofthe second counter DAI is determined based on the number of bits of thefirst counter DAI when the number of bits of the first counter DAI isdifferent from the number of bits of the second counter DAI.

Advantageous Effects

According to embodiments of the present disclosure, the UE may transmita PUCCH including two or more HARQ-ACKs in one slot. In this case, thecoverage of the PUCCH may be increased by reducing the amount ofHARQ-ACK that may be possessed by each PUCCH.

Further, according to embodiments of the present disclosure, there is aneffect that HARQ-ACK information on the PDSCH scheduled by downlinkcontrol information having a different format may be multiplexed andtransmitted.

In addition, according to embodiments of the present disclosure,HARQ-ACK information on the PDSCH scheduled by different downlinkcontrol information is multiplexed and transmitted, and thus an effectof reducing the signaling overhead for transmission of HARQ-Ackinformation is produced.

In addition, according to embodiments of the present disclosure, anHARQ-ACK bit(s) sequence having a small overhead of downlink controlinformation (e.g., DCI) may be determined, and thus an effect ofincreasing transmission efficiency of the network between the basestation and the UE is produced.

The effects obtainable from the present disclosure are not limited tothe effects mentioned above, and other effects not mentioned may beclearly understood by those skilled in the art from the followingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless frame structure used in awireless communication system.

FIG. 2 illustrates an example of a downlink (DL)/uplink (UL) slotstructure in a wireless communication system.

FIG. 3 is a diagram for explaining a physical channel used in a 3GPPsystem and a typical signal transmission method using the physicalchannel.

FIG. 4 illustrates an SS/PBCH block for initial cell access in a 3GPP NRsystem.

FIG. 5 illustrates a procedure for transmitting control information anda control channel in a 3GPP NR system.

FIG. 6 illustrates a control resource set (CORESET) in which a physicaldownlink control channel (PUCCH) may be transmitted in a 3GPP NR system.

FIG. 7 illustrates a method for configuring a PDCCH search space in a3GPP NR system.

FIG. 8 is a conceptual diagram illustrating carrier aggregation.

FIG. 9 is a diagram for explaining signal carrier communication andmultiple carrier communication.

FIG. 10 is a diagram showing an example in which a cross carrierscheduling technique is applied.

FIG. 11 is a block diagram illustrating configuration of a userequipment and a base station according to an embodiment of the presentdisclosure.

FIG. 12 is a flowchart illustrating an example of signaling between auser equipment and a base station to which an embodiment of the presentdisclosure is applicable.

FIG. 13 illustrates an example of a method for counting the number ofPDSCHs transmitted from a base station by a user equipment based on apseudo code that is applicable to an embodiment of the presentdisclosure.

FIG. 14 illustrates an example of a method for transmitting HARQ-Ackbased on downlink control information having a different formataccording to an embodiment of the present disclosure.

FIG. 15 illustrates another example of a method for transmitting aHARQ-Ack based on downlink control information having a different formataccording to an embodiment of the present disclosure.

FIG. 16 illustrates an example of a method for transmitting a HARQ-Ackbased on downlink control information for uplink and downlink schedulingaccording to an embodiment of the present disclosure.

FIG. 17 illustrates an example of a downlink assignment indicator ofeach piece of downlink control information detected in a monitoringoccasion according to an embodiment of the present disclosure.

FIG. 18 illustrates an example of a method for transmitting a HARQ-ACKbased on downlink control information having a different format based ona pseudo code according to an embodiment of the present disclosure.

FIG. 19 illustrates an example of a downlink assignment indicator ofeach piece of downlink control information detected in a monitoringoccasion according to an embodiment of the present disclosure.

FIG. 20 illustrates an example of a method for transmitting a HARQ-ACKfor a PDSCH according to a reception order of a PDCCH according to anembodiment of the present disclosure.

FIG. 21 illustrates an example of a method for transmitting a HARQ-ACKfor a PDSCH according to time information about a PDSCH according to anembodiment of the present disclosure.

FIG. 22 illustrates transmission of a HARQ-ACK for a PDSCH according toa HARQ process ID (or HARQ process number) of a PDCCH for scheduling thePDSCH according to an embodiment of the present disclosure.

FIG. 23 is a flowchart illustrating an example of an operation of a UEfor transmitting a HARQ-ACK based on downlink information having adifferent format according to an embodiment of the present disclosure.

FIG. 24 is a flowchart illustrating an example of an operation of a basestation for receiving a HARQ-ACK based on downlink information having adifferent format according to an embodiment of the present disclosure.

MODE FOR CARRYING OUT THE INVENTION

Terms used in the specification adopt general terms which are currentlywidely used as possible by considering functions in the presentinvention, but the terms may be changed depending on an intention ofthose skilled in the art, customs, and emergence of new technology.Further, in a specific case, there is a term arbitrarily selected by anapplicant and in this case, a meaning thereof will be described in acorresponding description part of the invention. Accordingly, it intendsto be revealed that a term used in the specification should be analyzedbased on not just a name of the term but a substantial meaning of theterm and contents throughout the specification.

Throughout this specification and the claims that follow, when it isdescribed that an element is “connected” to another element, the elementmay be “directly connected” to the other element or “electricallyconnected” to the other element through a third element. Further, unlessexplicitly described to the contrary, the word “comprise” will beunderstood to imply the inclusion of stated elements but not theexclusion of any other elements unless otherwise stated. Moreover,limitations such as “more than or equal to” or “less than or equal to”based on a specific threshold may be appropriately substituted with“more than” or “less than”, respectively, in some exemplary embodiments.

The following technology may be used in various wireless access systems,such as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier-FDMA(SC-FDMA), and the like. The CDMA may be implemented by a wirelesstechnology such as universal terrestrial radio access (UTRA) orCDMA2000. The TDMA may be implemented by a wireless technology such asglobal system for mobile communications (GSM)/general packet radioservice (GPRS)/enhanced data rates for GSM evolution (EDGE). The OFDMAmay be implemented by a wireless technology such as IEEE 802.11 (Wi-Fi),IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA), and the like.The UTRA is a part of a universal mobile telecommunication system(UMTS). 3rd generation partnership project (3GPP) long term evolution(LTE) is a part of an evolved UMTS (E-UMTS) using evolved-UMTSterrestrial radio access (E-UTRA) and LTE-advanced (A) is an evolvedversion of the 3GPP LTE. 3GPP new radio (NR) is a system designedseparately from LTE/LTE-A, and is a system for supporting enhancedmobile broadband (eMBB), ultra-reliable and low latency communication(URLLC), and massive machine type communication (mMTC) services, whichare requirements of IMT-2020. For the clear description, 3GPP NR ismainly described, but the technical idea of the present invention is notlimited thereto.

Unless otherwise specified in this specification, a base station mayrefer to a next generation node B (gNB) as defined in 3GPP NR.Furthermore, unless otherwise specified, a terminal may refer to a userequipment (UE).

Although details of the description are separately categorized intoembodiments below to assist with an understanding, the embodiments maybe used in combination. In the present disclosure, a configuration of auser equipment may represent a configuration by a base station. Indetail, a base station may transmit a signal to a user equipment to seta parameter value used in operation of the user equipment or a wirelesscommunication system.

FIG. 1 illustrates an example of a wireless frame structure used in awireless communication system. Referring to FIG. 1 , the wireless frame(or radio frame) used in the 3GPP NR system may have a length of 10 ms(Δf_(max)N_(f)/100)*T_(c)). In addition, the wireless frame includes 10subframes (SFs) having equal sizes. Herein, Δf_(max)480*10³ Hz,N_(f)=4096, T_(c)=1/(Δf_(ref)*N_(f),ref), Δf_(ref)=15*10³ Hz, andN_(f,ref)=2048. Numbers from 0 to 9 may be respectively allocated to 10subframes within one wireless frame. Each subframe has a length of 1 msand may include one or more slots according to a subcarrier spacing.More specifically, in the 3GPP NR system, the subcarrier spacing thatmay be used is 15*2 ^(μ) kHz, and can have a value of =0-4 as subcarrierspacing configuration. That is, 15 kHz, 30 kHz, 60 kHz, 120 kHz and 240kHz may be used for subcarrier spacing. One subframe having a length of1 ms may include 2^(μ) slots. In this case, the length of each slot is2^(−μ)ms. Numbers from 0 to 2^(μ)-1 may be respectively allocated to 2slots within one subframe. In addition, numbers from 0 to 10*2^(μ)-1 maybe respectively allocated to slots within one wireless frame. The timeresource may be distinguished by at least one of a wireless frame number(also referred to as a wireless frame index), a subframe number (alsoreferred to as a subframe index), and a slot number (or a slot index).

FIG. 2 illustrates an example of a downlink (DL)/uplink (UL) slotstructure in a wireless communication system. In particular, FIG. 2shows the structure of the resource grid of the 3GPP NR system.

There is one resource grid per antenna port. Referring to FIG. 2 , aslot includes a plurality of orthogonal frequency division multiplexing(OFDM) symbols in a time domain and includes a plurality of resourceblocks (RBs) in a frequency domain. An OFDM symbol also means one symbolsection. Unless otherwise specified, OFDM symbols may be referred tosimply as symbols. One RB includes 12 successive subcarriers in afrequency domain. Referring to FIG. 2 , a signal transmitted from eachslot may be represented by a resource grid includingN^(size,μ)g_(rid,X)*N^(RB) _(sc) subcarriers, and N^(slot) _(symb) OFDMsymbols. Here, x=DL when the signal is a DL signal, and x=UL when thesignal is an UL signal. N^(size,μ) _(grid,X) represents the number ofresource blocks (RBs) according to the subcarrier spacing constituent (xis DL or UL), and N^(slot) _(symb) represents the number of OFDM symbolsin a slot. N^(RB) _(sc) is the number of subcarriers constituting one RBand N^(RB) _(sc)=12. An OFDM symbol may be referred to as a cyclic shiftOFDM (CP-OFDM) symbol or a discrete Fourier transform spread OFDM(DFT-s-OFDM) symbol according to a multiple access scheme.

The number of OFDM symbols included in one slot may vary according tothe length of a cyclic prefix (CP). For example, in the case of a normalCP, one slot includes 14 OFDM symbols, but in the case of an extendedCP, one slot may include 12 OFDM symbols. In a specific embodiment, theextended CP can only be used at 60 kHz subcarrier spacing. In FIG. 2 ,for convenience of description, one slot is configured with 14 OFDMsymbols by way of example, but embodiments of the present disclosure maybe applied in a similar manner to a slot having a different number ofOFDM symbols. Referring to FIG. 2 , each OFDM symbol includes N^(size,μ)_(grid,x)*N^(RB) _(sc) subcarriers in the frequency domain. The type ofsubcarrier may be divided into a data subcarrier for data transmission,a reference signal subcarrier for transmission of a reference signal,and a guard band. The carrier frequency is also referred to as thecenter frequency (fc).

One RB may be defined by N^(RB) _(sc) (e. g., 12) consecutivesubcarriers in the frequency domain. For reference, a resourceconfigured with one OFDM symbol and one subcarrier may be referred to asa resource element (RE) or a tone. Therefore, one RB can be configuredwith N^(slot) _(symb)*N^(RB) _(sc) resource elements. Each resourceelement in the resource grid can be uniquely defined by a pair ofindexes (k, 1) in one slot. k may be an index assigned from 0 toN^(size,μ) _(grid, x)*N^(RB) _(sc)−1 in the frequency domain, and 1 maybe an index assigned from 0 to N^(slot) _(symb)−1 in the time domain.

In order for the UE to receive a signal from the base station or totransmit a signal to the base station, the time/frequency of the UE maybe synchronized with the time/frequency of the base station. This isbecause when the base station and the UE are synchronized, the UE candetermine the time and frequency parameters necessary for demodulatingthe DL signal and transmitting the UL signal at the correct time.

Each symbol of a radio frame used in a time division duplex (TDD) or anunpaired spectrum may be configured with at least one of a DL symbol, anUL symbol, and a flexible symbol. A radio frame used as a DL carrier ina frequency division duplex (FDD) or a paired spectrum may be configuredwith a DL symbol or a flexible symbol, and a radio frame used as a ULcarrier may be configured with a UL symbol or a flexible symbol. In theDL symbol, DL transmission is possible, but UL transmission isimpossible. In the UL symbol, UL transmission is possible, but DLtransmission is impossible. The flexible symbol may be determined to beused as a DL or an UL according to a signal.

Information on the type of each symbol, i.e., information representingany one of DL symbols, UL symbols, and flexible symbols, may beconfigured with a cell-specific or common radio resource control (RRC)signal. In addition, information on the type of each symbol mayadditionally be configured with a UE-specific or dedicated RRC signal.The base station informs, by using cell-specific RRC signals, i) theperiod of cell-specific slot configuration, ii) the number of slots withonly DL symbols from the beginning of the period of cell-specific slotconfiguration, iii) the number of DL symbols from the first symbol ofthe slot immediately following the slot with only DL symbols, iv) thenumber of slots with only UL symbols from the end of the period of cellspecific slot configuration, and v) the number of UL symbols from thelast symbol of the slot immediately before the slot with only the ULsymbol. Here, symbols not configured with any one of a UL symbol and aDL symbol are flexible symbols.

When the information on the symbol type is configured with theUE-specific RRC signal, the base station may signal whether the flexiblesymbol is a DL symbol or an UL symbol in the cell-specific RRC signal.In this case, the UE-specific RRC signal cannot change a DL symbol or aUL symbol configured with the cell-specific RRC signal into anothersymbol type. The UE-specific RRC signal may signal the number of DLsymbols among the N^(slot) _(symb) symbols of the corresponding slot foreach slot, and the number of UL symbols among the N_(slot) ^(symb)symbols of the corresponding slot. In this case, the DL symbol of theslot may be continuously configured with the first symbol to the i-thsymbol of the slot. In addition, the UL symbol of the slot may becontinuously configured with the j-th symbol to the last symbol of theslot (where i<j). In the slot, symbols not configured with any one of aUL symbol and a DL symbol are flexible symbols.

FIG. 3 is a diagram for explaining a physical channel used in a 3GPPsystem (e.g., NR) and a typical signal transmission method using thephysical channel.

If the power of the UE is turned on or the UE camps on a new cell, theUE performs an initial cell search (S101). Specifically, the UE maysynchronize with the BS in the initial cell search. For this, the UE mayreceive a primary synchronization signal (PSS) and a secondarysynchronization signal (SSS) from the base station to synchronize withthe base station, and obtain information such as a cell ID. Thereafter,the UE can receive the physical broadcast channel from the base stationand obtain the broadcast information in the cell.

Upon completion of the initial cell search, the UE receives a physicaldownlink shared channel (PDSCH) according to the physical downlinkcontrol channel (PDCCH) and information in the PDCCH, so that the UE canobtain more specific system information than the system informationobtained through the initial cell search (S102).

Here, the system information received by the user equipment iscell-common system information for the user equipment to correctlyoperate in a physical layer in radio resource control (RRC), and isreferred to as remaining system information or system information block(SIB).

When the UE initially accesses the base station or does not have radioresources for signal transmission, the UE may perform a random accessprocedure on the base station (operations S103 to S106). First, the UEcan transmit a preamble through a physical random access channel (PRACH)(S103) and receive a response message for the preamble from the basestation through the PDCCH and the corresponding PDSCH (S104). When avalid random access response message is received by the UE, the UEtransmits data including the identifier of the UE and the like to thebase station through a physical uplink shared channel (PUSCH) indicatedby the UL grant transmitted through the PDCCH from the base station(S105). Next, the UE waits for reception of the PDCCH as an indicationof the base station for collision resolution. If the UE successfullyreceives the PDCCH through the identifier of the UE (S106), the randomaccess process is terminated. The user equipment may obtainterminal-specific system information required for the user equipment tocorrectly operate in a physical layer in an RRC layer during a randomaccess process. When the user equipment obtains the terminal-specificsystem information from the RRC layer, the user equipment enters an RRCconnected mode.

The RRC layer is used to generate and manage a message between the userequipment and a radio access network (RAN). In more detail, the basestation and the user equipment may perform, in the RRC layer,broadcasting of cell system information required for all user equipmentsin a cell, management of transfer of a paging message, mobilitymanagement and handover, measurement report of the user equipment and acontrol therefor, and storage management including user equipmentcapability management and device management. In general, since update ofa signal transferred in the RRC layer (hereinafter, RRC signal) islonger than a transmission/reception period (i.e., transmission timeinterval (TTI)) in a physical layer, the RRC signal may be maintainedfor a long period without being changed.

After the above-described procedure, the UE receives PDCCH/PDSCH (S107)and transmits a physical uplink shared channel (PUSCH)/physical uplinkcontrol channel (PUCCH) (S108) as a general UL/DL signal transmissionprocedure. In particular, the UE may receive downlink controlinformation (DCI) through the PDCCH. The DCI may include controlinformation such as resource allocation information for the UE. Also,the format of the DCI may vary depending on the intended use. The uplinkcontrol information (UCI) that the UE transmits to the base stationthrough UL includes a DL/UL ACK/NACK signal, a channel quality indicator(CQI), a precoding matrix index (PMI), a rank indicator (RI), and thelike. Here, the CQI, PMI, and RI may be included in channel stateinformation (CSI). In the 3GPP NR system, the UE may transmit controlinformation such as HARQ-ACK and CSI described above through the PUSCHand/or PUCCH.

FIG. 4 illustrates an SS/PBCH block for initial cell access in a 3GPP NRsystem. When the power is turned on or wanting to access a new cell, theUE may obtain time and frequency synchronization with the cell andperform an initial cell search procedure. The UE may detect a physicalcell identity N^(cell) _(ID) of the cell during a cell search procedure.For this, the UE may receive a synchronization signal, for example, aprimary synchronization signal (PSS) and a secondary synchronizationsignal (SSS), from a base station, and synchronize with the basestation. In this case, the UE can obtain information such as a cellidentity (ID).

Referring to FIG. 4A, a synchronization signal (SS) will be described inmore detail. The synchronization signal can be classified into PSS andSSS. The PSS may be used to obtain time domain synchronization and/orfrequency domain synchronization, such as OFDM symbol synchronizationand slot synchronization. The SSS can be used to obtain framesynchronization and cell group ID. Referring to FIG. 4A and Table 2, theSS/PBCH block can be configured with consecutive 20 RBs (=240subcarriers) in the frequency axis, and can be configured withconsecutive 4 OFDM symbols in the time axis. In this case, in theSS/PBCH block, the PSS is transmitted in the first OFDM symbol and theSSS is transmitted in the third OFDM symbol through the 56th to 182thsubcarriers. Here, the lowest subcarrier index of the SS/PBCH block isnumbered from 0. In the first OFDM symbol in which the PSS istransmitted, the base station does not transmit a signal through theremaining subcarriers, i.e., 0th to 55th and 183th to 239th subcarriers.In addition, in the third OFDM symbol in which the SSS is transmitted,the base station does not transmit a signal through 48th to 55th and183th to 191th subcarriers. The base station transmits a physicalbroadcast channel (PBCH) through the remaining RE except for the abovesignal in the SS/PBCH block.

TABLE 1 OFDM symbol number l relative to the start of Subcarrier numberk Channel an SS/PBCH relative to the start or signal block of an SS/PBCHblock PSS 0 56, 57, . . . , 182 SSS 2 56, 57, . . . , 182 Set to 0 0 0,1, . . . , 55, 183, 184, . . . , 239 2 48, 49, . . . , 55, 183, 184, . .. , 191 PBCH 1, 3 0, 1, . . . , 239 2 0, 1, . . . , 47, 192, 193, . . ., 239 DM-RS 1, 3 0 + v, 4 + v, 8 + v, . . . , 236 + v for 2 0 + v, 4 +v, 8 + v, . . . 44 + v, PBCH 192 + v, 196 + v, . . . , 236 + v

The SS allows a total of 1008 unique physical layer cell IDs to begrouped into 336 physical-layer cell-identifier groups, each groupincluding three unique identifiers, through a combination of three PSSsand SSSs, specifically, such that each physical layer cell ID is to beonly a part of one physical-layer cell-identifier group. Therefore, thephysical layer cell ID N^(Cell) _(ID)=3N⁽¹⁾ _(ID)+N⁽²⁾ID can be uniquelydefined by the index N⁽¹⁾ _(ID) ranging from 0 to 335 indicating aphysical-layer cell-identifier group and the index N⁽²⁾ _(ID) rangingfrom 0 to 2 indicating a physical-layer identifier in the physical-layercell-identifier group. The UE may detect the PSS and identify one of thethree unique physical-layer identifiers. In addition, the UE can detectthe SSS and identify one of the 336 physical layer cell IDs associatedwith the physical-layer identifier. In this case, the sequenced_(Pss)(n) of the PSS is as follows.

d _(PSS)(n)=1−2x(m)

m=n+43_(ID) ⁽²⁾)mod 127

0≤n<127

Here, x(i+7)=(x(i+4)+x(i))mod2 and is given as

[x(6) x(5) x(4) x(3) x(2) x(i) x(0)]-[1 1 1 0 1 1 0]

Further, the sequence d_(SSS)(n) of the SSS is as follows.

d_(sss)(n) = [1 − 2x₀((n + m₀)mod127)][1 − 2x₁((n + m₁)mod127)]$m_{0} = {{15\left\lfloor \frac{N_{ID}^{(1)}}{112} \right\rfloor} + {5N_{ID}^{(2)}}}$m₁ = N_(ID)⁽¹⁾mod112 0 ≤ n < 127 x₀(i + 7) = (x₀(i + 4) + x₀(i))mod2

Here, x₁ (i+7)=(x₁(i+1)+x₁(i) mod2 and is given as

-   -   [x₀(6) x₀(5) x₀(4) x₀(3) x₀(2) X₀(1) X₀(0)]=[0 0 0 0 0 1]    -   [x₁(6) x₁(5) x₁(4) X₁(3) x₁(2) x₁(0) x(0)]=[0 0 0 0 0 0].

A radio frame with a 10 ms length may be divided into two half frameswith a 5 ms length. Referring to FIG. 4B, a description will be made ofa slot in which SS/PBCH blocks are transmitted in each half frame. Aslot in which the SS/PBCH block is transmitted may be any one of thecases A, B, C, D, and E. In the case A, the subcarrier spacing is 15 kHzand the starting time point of the SS/PBCH block is the ({2, 8}+14*n)-thsymbol. In this case, n=0 or 1 at a carrier frequency of 3 GHz or less.In addition, it may be n=0, 1, 2, 3 at carrier frequencies above 3 GHzand below 6 GHz. In the case B, the subcarrier spacing is 30 kHz and thestarting time point of the SS/PBCH block is {4, 8, 16, 20}+28*n. In thiscase, n=0 at a carrier frequency of 3 GHz or less. In addition, it maybe n=0, 1 at carrier frequencies above 3 GHz and below 6 GHz. In thecase C, the subcarrier spacing is 30 kHz and the starting time point ofthe SS/PBCH block is the ({2, 8}+14*n)-th symbol. In this case, n=0 or 1at a carrier frequency of 3 GHz or less. In addition, it may be n=0, 1,2, 3 at carrier frequencies above 3 GHz and below 6 GHz. In the case D,the subcarrier spacing is 120 kHz and the starting time point of theSS/PBCH block is the ({4, 8, 16, 20}+28*n)-th symbol. In this case, at acarrier frequency of 6 GHz or more, n=0, 1, 2, 3, 5, 6, 7, 8, 10, 11,12, 13, 15, 16, 17, 18. In the case E, the subcarrier spacing is 240 kHzand the starting time point of the SS/PBCH block is the ({8, 12, 16, 20,32, 36, 40, 44}+56*n)-th symbol. In this case, at a carrier frequency of6 GHz or more, n=0, 1, 2, 3, 5, 6, 7, 8.

FIG. 5 illustrates a procedure for transmitting control information anda control channel in a 3GPP NR system. Referring to FIG. 5A, the basestation may add a cyclic redundancy check (CRC) masked (e.g., an XORoperation) with a radio network temporary identifier (RNTI) to controlinformation (e.g., downlink control information (DCI)) (S202). The basestation may scramble the CRC with an RNTI value determined according tothe purpose/target of each control information. The common RNTI used byone or more UEs can include at least one of a system information RNTI(SI-RNTI), a paging RNTI (P-RNTI), a random access RNTI (RA-RNTI), and atransmit power control RNTI (TPC-RNTI). In addition, the UE-specificRNTI may include at least one of a cell temporary RNTI (C-RNTI), and theCS-RNTI. Thereafter, the base station may perform rate-matching (S206)according to the amount of resource(s) used for PDCCH transmission afterperforming channel encoding (e.g., polar coding) (S204). Thereafter, thebase station may multiplex the DCI(s) based on the control channelelement (CCE) based PDCCH structure (S208). In addition, the basestation may apply an additional process (S210) such as scrambling,modulation (e.g., QPSK), interleaving, and the like to the multiplexedDCI(s), and then map the DCI(s) to the resource to be transmitted. TheCCE is a basic resource unit for the PDCCH, and one CCE may include aplurality (e.g., six) of resource element groups (REGs). One REG may beconfigured with a plurality (e.g., 12) of REs. The number of CCEs usedfor one PDCCH may be defined as an aggregation level. In the 3GPP NRsystem, an aggregation level of 1, 2, 4, 8, or 16 may be used. FIG. 5Bis a diagram related to a CCE aggregation level and the multiplexing ofa PDCCH and illustrates the type of a CCE aggregation level used for onePDCCH and CCE(s) transmitted in the control area according thereto.

FIG. 6 illustrates a control resource set (CORESET) in which a physicaldownlink control channel (PUCCH) may be transmitted in a 3GPP NR system.

The CORESET is a time-frequency resource in which PDCCH, that is, acontrol signal for the UE, is transmitted. In addition, a search spaceto be described later may be mapped to one CORESET. Therefore, the UEmay monitor the time-frequency domain designated as CORESET instead ofmonitoring all frequency bands for PDCCH reception, and decode the PDCCHmapped to CORESET. The base station may configure one or more CORESETsfor each cell to the UE. The CORESET may be configured with up to threeconsecutive symbols on the time axis. In addition, the CORESET may beconfigured in units of six consecutive PRBs on the frequency axis. Inthe embodiment of FIG. 5 , CORESET #1 is configured with consecutivePRBs, and CORESET #2 and CORESET #3 are configured with discontinuousPRBs. The CORESET can be located in any symbol in the slot. For example,in the embodiment of FIG. 5 , CORESET #1 starts at the first symbol ofthe slot, CORESET #2 starts at the fifth symbol of the slot, and CORESET#9 starts at the ninth symbol of the slot.

FIG. 7 illustrates a method for setting a PDCCH search space in a 3GPPNR system.

In order to transmit the PDCCH to the UE, each CORESET may have at leastone search space. In the embodiment of the present disclosure, thesearch space is a set of all time-frequency resources (hereinafter,PDCCH candidates) through which the PDCCH of the UE is capable of beingtransmitted. The search space may include a common search space that theUE of the 3GPP NR is required to commonly search and a Terminal-specificor a UE-specific search space that a specific UE is required to search.In the common search space, UE may monitor the PDCCH that is set so thatall UEs in the cell belonging to the same base station commonly search.In addition, the UE-specific search space may be set for each UE so thatUEs monitor the PDCCH allocated to each UE at different search spaceposition according to the UE. In the case of the UE-specific searchspace, the search space between the UEs may be partially overlapped andallocated due to the limited control area in which the PDCCH may beallocated. Monitoring the PDCCH includes blind decoding for PDCCHcandidates in the search space. When the blind decoding is successful,it may be expressed that the PDCCH is (successfully) detected/receivedand when the blind decoding fails, it may be expressed that the PDCCH isnot detected/not received, or is not successfully detected/received.

For convenience of explanation, a PDCCH scrambled with a group common(GC) RNTI previously known to UEs so as to transmit DL controlinformation to the one or more UEs is referred to as a group common (GC)PDCCH or a common PDCCH. In addition, a PDCCH scrambled with aspecific-terminal RNTI that a specific UE already knows so as totransmit UL scheduling information or DL scheduling information to thespecific UE is referred to as a specific-UE PDCCH. The common PDCCH maybe included in a common search space, and the UE-specific PDCCH may beincluded in a common search space or a UE-specific PDCCH.

The base station may signal each UE or UE group through a PDCCH aboutinformation (i.e., DL Grant) related to resource allocation of a pagingchannel (PCH) and a downlink-shared channel (DL-SCH) that are atransmission channel or information (i.e., UL grant) related to resourceallocation of an uplink-shared channel (UL-SCH) and a hybrid automaticrepeat request (HARQ). The base station may transmit the PCH transportblock and the DL-SCH transport block through the PDSCH. The base stationmay transmit data excluding specific control information or specificservice data through the PDSCH. In addition, the UE may receive dataexcluding specific control information or specific service data throughthe PDSCH.

The base station may include, in the PDCCH, information on to which UE(one or a plurality of UEs) PDSCH data is transmitted and how the PDSCHdata is to be received and decoded by the corresponding UE, and transmitthe PDCCH. For example, it is assumed that the DCI transmitted through aspecific PDCCH is CRC masked with an RNTI of “A”, and the DCI indicatesthat PDSCH is allocated to a radio resource (e.g., frequency location)of “B” and indicates transmission format information (e.g., transportblock size, modulation scheme, coding information, etc.) of “C”. The UEmonitors the PDCCH using the RNTI information that the UE has. In thiscase, if there is a UE which performs blind decoding the PDCCH using the“A” RNTI, the UE receives the PDCCH, and receives the PDSCH indicated by“B” and “C” through the received PDCCH information.

Table 2 shows an embodiment of a physical uplink control channel (PUCCH)used in a wireless communication system.

TABLE 2 Length PUCCH in OFDM Number format symbols of bits 0 1-2 ≤2 1 4-14 ≤2 2 1-2 >2 3  4-14 >2 4  4-14 >2

PUCCH may be used to transmit the following UL control information(UCI).

-   -   Scheduling Request (SR): Information used for requesting a UL        UL-SCH resource.    -   HARQ-ACK: A Response to PDCCH (indicating DL SPS release) and/or        a response to DL transport block (TB) on PDSCH. HARQ-ACK        indicates whether information transmitted on the PDCCH or PDSCH        is received. The HARQ-ACK response includes positive ACK (simply        ACK), negative ACK (hereinafter NACK), Discontinuous        Transmission (DTX), or NACK/DTX. Here, the term HARQ-ACK is used        mixed with HARQ-ACK/NACK and ACK/NACK. In general, ACK may be        represented by bit value 1 and NACK may be represented by bit        value 0.    -   Channel State Information (CSI): Feedback information on the DL        channel. The UE generates it based on the CSI-Reference Signal        (RS) transmitted by the base station. Multiple Input Multiple        Output (MIMO)-related feedback information includes a Rank        Indicator (RI) and a Precoding Matrix Indicator (PMI). CSI can        be divided into CSI part 1 and CSI part 2 according to the        information indicated by CSI.

In the 3GPP NR system, five PUCCH formats may be used to support variousservice scenarios, various channel environments, and frame structures.

PUCCH format 0 is a format for transferring 1-bit or 2-bit HARQ-ACKinformation or SR. PUCCH format 0 may be transmitted through one or twoOFDM symbols on the time axis and one PRB on the frequency axis. WhenPUCCH format 0 is transmitted through two OFDM symbols, the samesequence on the two symbols may be transmitted through different RB.Here, the sequence may be a sequence cyclic-shifted (CS) from a basesequence used in PUCCH format 0. In this manner, the user equipment mayobtain a frequency diversity gain. In detail, the user equipment maydetermine a cyclic shift (CS) value m_(cs) according to Mbit bit UCI(M_(bit)=1 or 2). Furthermore, a sequence obtained by cyclic-shifting abase sequence having a length of 12 on the basis of the determined CSvalue m_(cs) may be mapped to one OFDM symbol and 12 REs of one RB so asto be transmitted. When the number of cyclic shifts available for theuser equipment is 12 and M_(bit)=1, 1 bit UCI 0 and 1 may be mapped totwo cyclic-shifted sequences having a cyclic shift value difference of6. Furthermore, when M_(bit)=2, 2-bit UCI 00, 01, 11, and 10 may berespectively mapped to four cyclic-shifted sequences having a cyclicshift value difference of 3.

PUCCH format 1 may deliver 1-bit or 2-bit HARQ-ACK information or SR.PUCCH format 1 maybe transmitted through consecutive OFDM symbols on thetime axis and one PRB on the frequency axis. Here, the number of OFDMsymbols occupied by PUCCH format 1 may be one of 4 to 14. Morespecifically, UCI, which is M_(bit)=1, may be BPSK-modulated. The UE maymodulate UCI, which is M_(bit)=2, with quadrature phase shift keying(QPSK). A signal is obtained by multiplying a modulated complex valuedsymbol d(0) by a sequence of length 12. In this case, the sequence maybe a base sequence used for PUCCH format 0. The UE spreads theeven-numbered OFDM symbols to which PUCCH format 1 is allocated throughthe time axis orthogonal cover code (OCC) to transmit the obtainedsignal. PUCCH format 1 determines the maximum number of different UEsmultiplexed in the one RB according to the length of the OCC to be used.A demodulation reference signal (DMRS) may be spread with OCC and mappedto the odd-numbered OFDM symbols of PUCCH format 1.

PUCCH format 2 may deliver UCI exceeding 2 bits. PUCCH format 2 may betransmitted through one or two OFDM symbols on the time axis and one ora plurality of RBs on the frequency axis. When PUCCH format 2 istransmitted in two OFDM symbols, the sequences which are transmitted indifferent RBs through the two OFDM symbols may be same each other. Here,the sequence may be a plurality of modulated complex valued symbolsd(0), . . . , d(M_(symbol)-1). Here, M_(symbol) may be M_(bit)/2.Through this, the UE may obtain a frequency diversity gain. Morespecifically, M_(bit) bit UCI (M_(bit)>2) is bit-level scrambled, QPSKmodulated, and mapped to RB(s) of one or two OFDM symbol(s). Here, thenumber of RBs may be one of 1 to 16.

PUCCH format 3 or PUCCH format 4 may deliver UCI exceeding 2 bits. PUCCHformat 3 or PUCCH format 4 may be transmitted through consecutive OFDMsymbols on the time axis and one PRB on the frequency axis. The numberof OFDM symbols occupied by PUCCH format 3 or PUCCH format 4 may be oneof 4 to 14. Specifically, the UE modulates M_(bit) bits UCI (M_(bit)>2)with π/2-Binary Phase Shift Keying (BPSK) or QPSK to generate a complexvalued symbol d(0) to d(M_(symb)-1). Here, when using π/2-BPSK,M_(symb)=M_(bit), and when using QPSK, M_(symb)=M_(bit)/2. The UE maynot apply block-unit spreading to the PUCCH format 3. However, the UEmay apply block-unit spreading to one RB (i.e., 12 subcarriers) usingPreDFT-OCC of a length of 12 such that PUCCH format 4 may have two orfour multiplexing capacities. The UE performs transmit precoding (orDFT-precoding) on the spread signal and maps it to each RE to transmitthe spread signal.

In this case, the number of RBs occupied by PUCCH format 2, PUCCH format3, or PUCCH format 4 may be determined according to the length andmaximum code rate of the UCI transmitted by the UE. When the UE usesPUCCH format 2, the UE may transmit HARQ-ACK information and CSIinformation together through the PUCCH. When the number of RBs that theUE may transmit is greater than the maximum number of RBs that PUCCHformat 2, or PUCCH format 3, or PUCCH format 4 may use, the UE maytransmit only the remaining UCI information without transmitting someUCI information according to the priority of the UCI information.

PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configuredthrough the RRC signal to indicate frequency hopping in a slot. Whenfrequency hopping is configured, the index of the RB to be frequencyhopped may be configured with an RRC signal. When PUCCH format 1, PUCCHformat 3, or PUCCH format 4 is transmitted through N OFDM symbols on thetime axis, the first hop may have floor (N/2) OFDM symbols and thesecond hop may have ceiling(N/2) OFDM symbols.

PUCCH format 1, PUCCH format 3, or PUCCH format 4 may be configured tobe repeatedly transmitted in a plurality of slots. In this case, thenumber K of slots in which the PUCCH is repeatedly transmitted may beconfigured by the RRC signal. The repeatedly transmitted PUCCHs muststart at an OFDM symbol of the constant position in each slot, and havethe constant length. When one OFDM symbol among OFDM symbols of a slotin which a UE should transmit a PUCCH is indicated as a DL symbol by anRRC signal, the UE may not transmit the PUCCH in a corresponding slotand delay the transmission of the PUCCH to the next slot to transmit thePUCCH.

Meanwhile, in the 3GPP NR system, the user equipment may performtransmission/reception using a bandwidth that is smaller than or equalto the bandwidth of a carrier (or cell). To this end, the user mayreceive a configuration of bandwidth part (BWP) configured with apartial continuous bandwidth of the bandwidth of a carrier. The userequipment which operates according to TDD or operates in an unpairedspectrum may receive a configuration of up to four DL/UL BWP pairs inone carrier (cell). Furthermore, the user equipment may activate oneDL/UL BWP pair. The user equipment which operates according to FDD oroperates in a paired spectrum may receive a configuration of up to fourDL BWPs in a downlink carrier (or cell) and a configuration of up tofour UL BWPs in an uplink carrier (or cell). The user equipment mayactivate one DL BWP and UL BWP for each carrier (or cell). The userequipment may not receive or transmit on a time-frequency resourceexcept for activated BWP. The activated BWP may be referred to as activeBWP.

The base station may indicate an activated BWP among BWPs configured forthe user equipment through downlink control information (DCI). A BWPindicated through DCI is activated, and other configured BWP(s) aredeactivated. In a carrier (or cell) operating according to TDD, the basestation may add a bandwidth part indicator (BPI) indicating a BWP to beactivated to the DCI that schedules PDSCH or PUSCH in order to change aDL/UL BWP pair of the user equipment. The user equipment may receive theDCI that schedules PDSCH or PUSCH, and may identify a DL/UL BWP pair tobe activated on the basis of the BPI. In the case of a downlink carrier(or cell) operating according to FDD, the base station may add a BPIindicating a BWP to be activated to the DCI that schedules PDSCH inorder to change a DL BWP of the base station. In the case of an uplinkcarrier (or cell) operating according to FDD, the base station may add aBPI indicating a BWP to be activated to the DCI that schedules PUSCH inorder to change a UL BWP of the base station.

FIG. 8 is a conceptual diagram illustrating carrier aggregation.

The carrier aggregation is a method in which the UE uses a plurality offrequency blocks or cells (in the logical sense) configured with ULresources (or component carriers) and/or DL resources (or componentcarriers) as one large logical frequency band in order for a wirelesscommunication system to use a wider frequency band. One componentcarrier may also be referred to as a term called a Primary cell (PCell)or a Secondary cell (SCell), or a Primary SCell (PScell). However,hereinafter, for convenience of description, the term “componentcarrier” is used.

Referring to FIG. 8 , as an example of a 3GPP NR system, the entiresystem band may include up to 16 component carriers, and each componentcarrier may have a bandwidth of up to 400 MHz. The component carrier mayinclude one or more physically consecutive subcarriers. Although it isshown in FIG. 8 that each of the component carriers has the samebandwidth, this is merely an example, and each component carrier mayhave a different bandwidth. Also, although each component carrier isshown as being adjacent to each other in the frequency axis, thedrawings are shown in a logical concept, and each component carrier maybe physically adjacent to one another, or may be spaced apart.

Different center frequencies may be used for each component carrier.Also, one common center frequency may be used in physically adjacentcomponent carriers. Assuming that all the component carriers arephysically adjacent in the embodiment of FIG. 8 , center frequency A maybe used in all the component carriers. Further, assuming that therespective component carriers are not physically adjacent to each other,center frequency A and the center frequency B can be used in each of thecomponent carriers.

When the total system band is extended by carrier aggregation, thefrequency band used for communication with each UE can be defined inunits of a component carrier. UE A may use 100 MHz, which is the totalsystem band, and performs communication using all five componentcarriers. UEs B₁-B₅ can use only a 20 MHz bandwidth and performcommunication using one component carrier. UEs C₁ and C₂ may use a 40MHz bandwidth and perform communication using two component carriers,respectively. The two component carriers may be logically/physicallyadjacent or non-adjacent. UE C₁ represents the case of using twonon-adjacent component carriers, and UE C₂ represents the case of usingtwo adjacent component carriers.

FIG. 9 is a drawing for explaining signal carrier communication andmultiple carrier communication. Particularly, FIG. 9A shows a singlecarrier subframe structure and FIG. 9B shows a multi-carrier subframestructure.

Referring to FIG. 9A, in an FDD mode, a general wireless communicationsystem may perform data transmission or reception through one DL bandand one UL band corresponding thereto. In another specific embodiment,in a TDD mode, the wireless communication system may divide a radioframe into a UL time unit and a DL time unit in a time domain, andperform data transmission or reception through a UL/DL time unit.Referring to FIG. 9B, three 20 MHz component carriers (CCs) can beaggregated into each of UL and DL, so that a bandwidth of 60 MHz can besupported. Each CC may be adjacent or non-adjacent to one another in thefrequency domain. FIG. 9B shows a case where the bandwidth of the UL CCand the bandwidth of the DL CC are the same and symmetric, but thebandwidth of each CC can be determined independently. In addition,asymmetric carrier aggregation with different number of UL CCs and DLCCs is possible. A DL/UL CC allocated/configured to a specific UEthrough RRC may be called as a serving DL/UL CC of the specific UE.

The base station may perform communication with the UE by activatingsome or all of the serving CCs of the UE or deactivating some CCs. Thebase station can change the CC to be activated/deactivated, and changethe number of CCs to be activated/deactivated. If the base stationallocates a CC available for the UE as to be cell-specific orUE-specific, at least one of the allocated CCs may not be deactivated,unless the CC allocation for the UE is completely reconfigured or the UEis handed over. One CC that is not deactivated by the UE is called as aPrimary CC (PCC) or a primary cell (PCell), and a CC that the basestation can freely activate/deactivate is called as a Secondary CC (SCC)or a secondary cell (SCell).

Meanwhile, 3GPP NR uses the concept of a cell to manage radio resources.A cell is defined as a combination of DL resources and UL resources,that is, a combination of DL CC and UL CC. A cell may be configured withDL resources alone, or a combination of DL resources and UL resources.When the carrier aggregation is supported, the linkage between thecarrier frequency of the DL resource (or DL CC) and the carrierfrequency of the UL resource (or UL CC) may be indicated by systeminformation. The carrier frequency refers to the center frequency ofeach cell or CC. A cell corresponding to the PCC is referred to as aPCell, and a cell corresponding to the SCC is referred to as an SCell.The carrier corresponding to the PCell in the DL is the DL PCC, and thecarrier corresponding to the PCell in the UL is the UL PCC. Similarly,the carrier corresponding to the SCell in the DL is the DL SCC and thecarrier corresponding to the SCell in the UL is the UL SCC. According toUE capability, the serving cell(s) may be configured with one PCell andzero or more SCells. In the case of UEs that are in the RRC_CONNECTEDstate but not configured for carrier aggregation or that do not supportcarrier aggregation, there is only one serving cell configured only withPCell.

As mentioned above, the term “cell” used in carrier aggregation isdistinguished from the term “cell” which refers to a certaingeographical area in which a communication service is provided by onebase station or one antenna group. That is, one component carrier mayalso be referred to as a scheduling cell, a scheduled cell, a primarycell (PCell), a secondary cell (SCell), or a primary SCell (PScell).However, in order to distinguish between a cell referring to a certaingeographical area and a cell of carrier aggregation, in the presentdisclosure, a cell of a carrier aggregation is referred to as a CC, anda cell of a geographical area is referred to as a cell.

FIG. 10 is a diagram showing an example in which a cross carrierscheduling technique is applied. When cross carrier scheduling is set,the control channel transmitted through the first CC may schedule a datachannel transmitted through the first CC or the second CC using acarrier indicator field (CIF). The CIF is included in the DCI. In otherwords, a scheduling cell is set, and the DL grant/UL grant transmittedin the PDCCH area of the scheduling cell schedules the PDSCH/PUSCH ofthe scheduled cell. That is, a search area for the plurality ofcomponent carriers exists in the PDCCH area of the scheduling cell. APCell may be basically a scheduling cell, and a specific SCell may bedesignated as a scheduling cell by an upper layer.

In the embodiment of FIG. 10 , it is assumed that three DL CCs aremerged. Here, it is assumed that DL component carrier #0 is DL PCC (orPCell), and DL component carrier #1 and DL component carrier #2 are DLSCCs (or SCell). In addition, it is assumed that the DL PCC is set tothe PDCCH monitoring CC. When cross-carrier scheduling is not configuredby UE-specific (or UE-group-specific or cell-specific) higher layersignaling, a CIF is disabled, and each DL CC can transmit only a PDCCHfor scheduling its PDSCH without the CIF according to an NR PDCCH rule(non-cross-carrier scheduling, self-carrier scheduling). Meanwhile, ifcross-carrier scheduling is configured by UE-specific (orUE-group-specific or cell-specific) higher layer signaling, a CIF isenabled, and a specific CC (e.g., DL PCC) may transmit not only thePDCCH for scheduling the PDSCH of the DL CC A using the CIF but also thePDCCH for scheduling the PDSCH of another CC (cross-carrier scheduling).On the other hand, a PDCCH is not transmitted in another DL CC.Accordingly, the UE monitors the PDCCH not including the CIF to receivea self-carrier scheduled PDSCH depending on whether the cross-carrierscheduling is configured for the UE, or monitors the PDCCH including theCIF to receive the cross-carrier scheduled PDSCH.

On the other hand, FIGS. 9 and 10 illustrate the subframe structure ofthe 3GPP LTE-A system, and the same or similar configuration may beapplied to the 3GPP NR system. However, in the 3GPP NR system, thesubframes of FIGS. 9 and 10 may be replaced with slots.

FIG. 11 is a block diagram showing the configurations of a UE and a basestation according to an embodiment of the present disclosure. In anembodiment of the present disclosure, the UE may be implemented withvarious types of wireless communication devices or computing devicesthat are guaranteed to be portable and mobile. The UE may be referred toas a User Equipment (UE), a Station (STA), a Mobile Subscriber (MS), orthe like. In addition, in an embodiment of the present disclosure, thebase station controls and manages a cell (e.g., a macro cell, a femtocell, a pico cell, etc.) corresponding to a service area, and performsfunctions of a signal transmission, a channel designation, a channelmonitoring, a self diagnosis, a relay, or the like. The base station maybe referred to as next Generation NodeB (gNB) or Access Point (AP).

As shown in the drawing, a UE 100 according to an embodiment of thepresent disclosure may include a processor 110, a communication module120, a memory 130, a user interface 140, and a display unit 150.

First, the processor 110 may execute various instructions or programsand process data within the UE 100. In addition, the processor 110 maycontrol the entire operation including each unit of the UE 100, and maycontrol the transmission/reception of data between the units. Here, theprocessor 110 may be configured to perform an operation according to theembodiments described in the present disclosure. For example, theprocessor 110 may receive slot configuration information, determine aslot configuration based on the slot configuration information, andperform communication according to the determined slot configuration.

Next, the communication module 120 may be an integrated module thatperforms wireless communication using a wireless communication networkand a wireless LAN access using a wireless LAN. For this, thecommunication module 120 may include a plurality of network interfacecards (NICs) such as cellular communication interface cards 121 and 122and an unlicensed band communication interface card 123 in an internalor external form. In the drawing, the communication module 120 is shownas an integral integration module, but unlike the drawing, each networkinterface card can be independently arranged according to a circuitconfiguration or usage.

The cellular communication interface card 121 may transmit or receive aradio signal with at least one of the base station 200, an externaldevice, and a server by using a mobile communication network and providea cellular communication service in a first frequency band based on theinstructions from the processor 110. According to an embodiment, thecellular communication interface card 121 may include at least one NICmodule using a frequency band of less than 6 GHz. At least one NICmodule of the cellular communication interface card 121 mayindependently perform cellular communication with at least one of thebase station 200, an external device, and a server in accordance withcellular communication standards or protocols in the frequency bandsbelow 6 GHz supported by the corresponding NIC module.

The cellular communication interface card 122 may transmit or receive aradio signal with at least one of the base station 200, an externaldevice, and a server by using a mobile communication network and providea cellular communication service in a second frequency band based on theinstructions from the processor 110. According to an embodiment, thecellular communication interface card 122 may include at least one NICmodule using a frequency band of more than 6 GHz. At least one NICmodule of the cellular communication interface card 122 mayindependently perform cellular communication with at least one of thebase station 200, an external device, and a server in accordance withcellular communication standards or protocols in the frequency bands of6 GHz or more supported by the corresponding NIC module.

The unlicensed band communication interface card 123 transmits orreceives a radio signal with at least one of the base station 200, anexternal device, and a server by using a third frequency band which isan unlicensed band, and provides an unlicensed band communicationservice based on the instructions from the processor 110. The unlicensedband communication interface card 123 may include at least one NICmodule using an unlicensed band. For example, the unlicensed band may bea band of 2.4 GHz or 5 GHz. At least one NIC module of the unlicensedband communication interface card 123 may independently or dependentlyperform wireless communication with at least one of the base station200, an external device, and a server according to the unlicensed bandcommunication standard or protocol of the frequency band supported bythe corresponding NIC module.

The memory 130 stores a control program used in the UE 100 and variouskinds of data therefor. Such a control program may include a prescribedprogram required for performing wireless communication with at least oneamong the base station 200, an external device, and a server.

Next, the user interface 140 includes various kinds of input/outputmeans provided in the UE 100. In other words, the user interface 140 mayreceive a user input using various input means, and the processor 110may control the UE 100 based on the received user input. In addition,the user interface 140 may perform an output based on instructions fromthe processor 110 using various kinds of output means.

Next, the display unit 150 outputs various images on a display screen.The display unit 150 may output various display objects such as contentexecuted by the processor 110 or a user interface based on controlinstructions from the processor 110.

In addition, the base station 200 according to an embodiment of thepresent disclosure may include a processor 210, a communication module220, and a memory 230.

First, the processor 210 may execute various instructions or programs,and process internal data of the base station 200. In addition, theprocessor 210 may control the entire operations of units in the basestation 200, and control data transmission and reception between theunits. Here, the processor 210 may be configured to perform operationsaccording to embodiments described in the present disclosure. Forexample, the processor 210 may signal slot configuration and performcommunication according to the signaled slot configuration.

Next, the communication module 220 may be an integrated module thatperforms wireless communication using a wireless communication networkand a wireless LAN access using a wireless LAN. For this, thecommunication module 120 may include a plurality of network interfacecards such as cellular communication interface cards 221 and 222 and anunlicensed band communication interface card 223 in an internal orexternal form. In the drawing, the communication module 220 is shown asan integral integration module, but unlike the drawing, each networkinterface card can be independently arranged according to a circuitconfiguration or usage.

The cellular communication interface card 221 may transmit or receive aradio signal with at least one of the base station 100, an externaldevice, and a server by using a mobile communication network and providea cellular communication service in the first frequency band based onthe instructions from the processor 210. According to an embodiment, thecellular communication interface card 221 may include at least one NICmodule using a frequency band of less than 6 GHz. The at least one NICmodule of the cellular communication interface card 221 mayindependently perform cellular communication with at least one of thebase station 100, an external device, and a server in accordance withthe cellular communication standards or protocols in the frequency bandsless than 6 GHz supported by the corresponding NIC module.

The cellular communication interface card 222 may transmit or receive aradio signal with at least one of the base station 100, an externaldevice, and a server by using a mobile communication network and providea cellular communication service in the second frequency band based onthe instructions from the processor 210. According to an embodiment, thecellular communication interface card 222 may include at least one NICmodule using a frequency band of 6 GHz or more. The at least one NICmodule of the cellular communication interface card 222 mayindependently perform cellular communication with at least one of thebase station 100, an external device, and a server in accordance withthe cellular communication standards or protocols in the frequency bands6 GHz or more supported by the corresponding NIC module.

The unlicensed band communication interface card 223 transmits orreceives a radio signal with at least one of the base station 100, anexternal device, and a server by using the third frequency band which isan unlicensed band, and provides an unlicensed band communicationservice based on the instructions from the processor 210. The unlicensedband communication interface card 223 may include at least one NICmodule using an unlicensed band. For example, the unlicensed band may bea band of 2.4 GHz or 5 GHz. At least one NIC module of the unlicensedband communication interface card 223 may independently or dependentlyperform wireless communication with at least one of the base station100, an external device, and a server according to the unlicensed bandcommunication standards or protocols of the frequency band supported bythe corresponding NIC module.

FIG. 11 is a block diagram illustrating the UE 100 and the base station200 according to an embodiment of the present disclosure, and blocksseparately shown are logically divided elements of a device.Accordingly, the aforementioned elements of the device may be mounted ina single chip or a plurality of chips according to the design of thedevice. In addition, a part of the configuration of the UE 100, forexample, a user interface 140, a display unit 150 and the like may beselectively provided in the UE 100. In addition, the user interface 140,the display unit 150 and the like may be additionally provided in thebase station 200, if necessary.

In the NR wireless communication system, the user equipment may transmita codebook including hybrid automatic repeat request (HARQ)-ACKinformation to signal whether reception of a downlink signal or channelhas succeeded. The HARQ-ACK codebook includes one or more bitsindicating whether reception of a downlink signal or channel hassucceeded. Here, the downlink channel may include at least one of aphysical downlink shared channel (PDSCH), a semi-persistence scheduling(SPS) PDSCH, and a PDCCH for releasing the SPS PDSCH. The HARQ-ACKcodebook may be divided into a semi-static HARQ-ACK codebook (orfirst-type codebook) and a dynamic HARQ-ACK codebook (or second-typecodebook). The base station may set one of the two HARQ-ACK codebooksfor the user equipment. The user equipment may use a HARQ-ACK codebookset for the user equipment.

When the semi-static HARQ-ACK codebook is used, the base station may usean RRC signal to configure the number of bits of the HARQ-ACK codebookand information for determining which downlink signal or channel issuccessfully received by each bit of the HARQ-ACK codebook. Therefore,it is not necessary for the base station to signal information requiredfor transmitting the HARQ-ACK codebook to the user equipment each timetransmission of the HARQ-ACK codebook is necessary.

When the dynamic HARQ-ACK codebook is used, the base station may signalinformation required for generating the HARQ-ACK codebook through aPDCCH (or DCI). In detail, the base station may signal the informationrequired for generating the HARQ-ACK codebook through a down assignmentindex (DAI) field of a PDCCH (or DCI). In a specific embodiment, a DAIrepresents information about the number of bits of the HARQ-ACK codebookand about for which channel or signal each bit of the HARQ-ACK codebookindicates reception success or failure. The user equipment may receivethe DAI field through a PDCCH (or DCI) for scheduling a PDSCH. A valueof the DAI field may be divided into a counter-DAI and a total DAI. Thetotal-DAI indicates the number of downlink signals or channels for whichreception success or failure is indicated through the HARQ-ACK codebookuntil a current monitoring occasion (MO). The counter-DAI indicates aHARQ-ACK codebook bit indicating reception success or failure ofdownlink signals or channels among the downlink signals or channels forwhich reception success or failure is indicated through the HARQ-ACKcodebook until a current cell of a current monitoring occasion. A PDCCH(or DCI) for scheduling a PDSCH may include a value of the counter-DAIcorresponding to a scheduled PDSCH. Furthermore, a PDCCH (or DCI) forscheduling a PDSCH may include a value of the total-DAI corresponding toa scheduled PDSCH. The user equipment may determine the number of bitsof the dynamic HARQ-ACK codebook on the basis of information signaled bya PDCCH (or DCI). In detail, the user equipment may determine the numberof bits of the dynamic HARQ-ACK codebook on the basis of the DAI of aPDCCH (or DCI).

FIG. 12 is a flowchart illustrating an example of signaling between auser equipment and a base station to which an embodiment of the presentdisclosure is applicable.

Referring to FIG. 12 , a UE receives, from a base station, RRCconfiguration information including information for receiving downlinkcontrol information (DCI)(S12010).

For example, the RRC configuration information may include informationrelated to a control resource set (CORSET) and a search space for the UEto detect a PDCCH including downlink control information. In this case,the information related to the control resource set may include at leastone of an identifier (ID) of a control resource set through which the UEmay detect the PDCCH including the DCI, control channel element (CCE)configuration information and control resource set length (duration), orfrequency resource information. In this case, information related to thesearch space may include at least one of an identifier (ID) of thesearch space through which the UE may detect the PDCCH including theDCI, a format of the DCI that may be detected in each search space, adetection duration, or resource information.

Then, the UE may receive the DCI by detecting the PDCCH in themonitoring occasion based on the RRC configuration information (S12020).The UE may acquire the DCI by detecting the PDCCH in a specific searchspace of the monitoring occasion according to the type of service and/ordata based on the RRC configuration information.

In this case, the DAI included in the DCI may be configured withdifferent bits according to the format of the DCI. For example, in DCIFormat 1_0, the DAI may be configured with 2 bits, and in DCI Format 11,may be configured with 1 bit for a semi-static HARQ-ACK codebook, andwith 2 bits for a dynamic-HARQ-ACK codebook.

Table 3 below shows an example of bits of DAI according to the DCIformat.

TABLE 3 Counter-DAI Total DAI UL DAI DCI format 0_0 — — — DCI format 0_1— — For TB-based transmission 2 bits For CBG transmission 4 bits (2 bitsfor TB-based reception, 2 bits for CBG-based reception) DCI format 0_2 —— if Downlinkassignmentindex- ForDCIFormat0_2 is not configured, 0 bitOtherwise, for TB-based reception 2 bits for CBG-based reception 4 bits(2 bits for TB-based reception, 2 bits for CBG-based reception) DCIformat 1_0 2 bits 0 bits — DCI format 1_1 2 bits 2 bits — DCI format 1_2if if — Downlinkassignmentindex- Downlinkassignmentindex-ForDCIFormat1_2 is not ForDCIFormat1_2 is not configured, configured, 0bit 0 bit Otherwise Otherwise 1 or 2 bits 0 bit or 2 bits

In addition, the UE may be allocated a resource for the reception of thePDSCH or the transmission of the PUSCH through the PDCCH (or DCI).

Then, the UE may receive the PDSCH or transmit the PUSCH to the basestation through the allocated resource(S12030). If the UE receives thePDSCH from the base station, the UE may generate a HARQ-ACK codebookindicating the ACK/NACK of the received PDSCH based on the DAI valueincluded in the PDCCH (or DCI) for scheduling of the PDSCH, andtransmit, to the base station, the generated HARQ-ACK codebook byincluding it in uplink control information (UCI) (S12040).

FIG. 13(a) and FIG. 13(b) illustrate an example of a method for countingthe number of PDSCHs transmitted from a base station by a user equipmentbased on a pseudo code that is applicable to an embodiment of thepresent disclosure.

(a) and (b) of FIG. 13 illustrates an example of a method for generatingand transmitting a HARQ-ACK codebook based on a stored counter-DAIvalue, a counter-DAI value transmitted through a specific DCI, and astored total-DAI value.

Specifically, referring to (a) of FIG. 13 , the UE may set thecounter-DAI value of the PDCCH (or DCI) received in a serving cell c ofa monitoring occasion m to be V_(c-DAI,c,m) ^(DL), the storedcounter-DAI value to be V_(temp), and the stored total-DAI value(total-DAI) to be V_(temp2). In this case, a range T_(D) of a value thatmay be expressed as the number of bits of the DAI may be calculated byEquation 1 below.

$\begin{matrix}{T_{D} = 2^{N_{C - {DAI}}^{DL}}} & \left\lbrack {{Equation}1} \right\rbrack\end{matrix}$

Here, the monitoring occasion index m and a cell index c are omitted.Tables 4 and 5 show ranges of values in which the counter-DAI ortotal-DAI is expressed according to the number of bits of thecounter-DAI or the number of bits of the total-DAI. Table 4 shows anexample when the number of bits of the counter-DAI or the number of bitsof the total-DAI is 2 bits, and Table 5 shows an example when the numberof bits of the counter-DAI or the number of bits of the

TABLE 4 Number of {serving cell, PDCCH monitoring occasion}-pair(s) inwhich PDSCH transmission(s) associated with PDCCH or PDCCH DAIindicating SPS PDSCH MSB, V_(C-DAI) ^(DL) or release is present, LSBV_(T-DAI) ^(DL) denoted as Y and Y ≥ 1 0, 0 1 (Y − 1) mod T_(D) + 1 = 10, 1 2 (Y − 1) mod T_(D) + 1 = 2 1, 0 3 (Y − 1) mod T_(D) + 1 = 3 1, 1 4(Y − 1) mod T_(D) + 1 = 4

TABLE 5 Number of {serving cell, PDCCH monitoring occasion}-pair(s) inwhich PDSCH transmission(s) associated with PDCCH or PDCCH indicatingSPS PDSCH release is present, DAI V_(C-DAI) ^(DL) denoted as Y and Y ≥ 10 1 (Y − 1) mod T_(D) + 1 = 1 1 2 (Y − 1) mod T_(D) + 1 = 2

In this case, the pseudo code for generating the HARQ-ACK codebook isshown in Table 6 below.

TABLE 6 Set m = 0 - PDCCH with DCI format scheduling PDSCH reception orSPS PDSCH release monitoring occasion index:  lower index corresponds toearlier PDCCH monitoring occasion Set j = 0 Set V_(temp) = 0 SetV_(temp2) = 0 Set V_(s) = Ø Set N_(cells) ^(DL) to the number of cellsconfigured by higher layers for the UE Set M to the number of PDCCHmonitoring occasion(s) while m < M   Set c = 0 - serving cell index:lower indexes correspond to lower RRC indexes of corresponding cell  while c < N_(cells) ^(DL)    if PDCCH monitoring occasion m is beforean active DL BWP change on serving cell c , or an active UL BWP   change on the PCell and an active DL BWP change is not triggered inthe PDCCH monitoring occasion m     c = c + 1,   else    if there is aPDSCH on serving cell c associated with PDCCH in PDCCH monitoringoccasion m , or there    is a PDCCH indicating SPS PDSCH release onserving cell c     if V_(C−DAI,c,m) ^(DL) ≤ V_(temp)      j = j + 1    end if     V_(temp) = V_(C−DAI,c,m) ^(DL)     if V_(T−DAI,m) ^(DL) =∅      V_(temp2) = V_(C−DAI,c,m) ^(DL)     else      V_(temp2) =V_(T−DAI,m) ^(DL)     end if     if harq-ACK-SpatialBundlingPUCCH is notprovided and the UE is configured by     maxNrofCodeWordsScheduledByDCIwith reception of two transport blocks for at least one configured DL    BWP of at least one serving cell,      ${\overset{\sim}{o}}_{{2 \cdot T_{D} \cdot j} + {2{({V_{{C - {DAI}},c,m}^{DL} - 1})}}}^{ACK} = {{HARQ} - {ACK}}$      information bit corresponding to the first transport block of thiscell      ${\overset{\sim}{o}}_{{2 \cdot T_{D} \cdot j} + {2{({V_{{C - {DAI}},c,m}^{DL} - 1})}} + 1}^{ACK} = {{HARQ} - {ACK}}$      information bit corresponding to the second transport block ofthis cell       V_(s) = V_(s) ∪ {2 · T_(D) · j + 2(V_(C−DAI,c,m) ^(DL) −1), 2 · T_(D) · j + 2(V_(C−DAI,c,m) ^(DL) − 1) + 1}      elseifharq-ACK-SpatialBundlingPUCCH is provided to the UE and m is amonitoring occasion for      PDCCH with DCI format that supports PDSCHreception with two transport blocks and the UE is      configured bymaxNrofCodeWordsScheduledByDCI with reception of two transport blocks inat least one      configured DL BWP of a serving cell,      ${\overset{\sim}{o}}_{{T_{D} \cdot j} + V_{{C - {DAI}},c,m}^{DL} - 1}^{ACK} = {{binary}{AND}{operation}{of}{the}{HARQ} - {ACK}}$      information bits corresponding to the  first and second transportblocks of this cell        V_(s) = V_(s) ∪ {T_(D) · j + V_(C−DAI,c,m)^(DL) − 1}     else      ${\overset{\sim}{o}}_{{T_{D} \cdot j} + V_{{C - {DAI}},c,m}^{DL} - 1}^{ACK} = {{HARQ} - {ACK}}$      information bit of this cell        V_(s) = V_(s) ∪ {T_(D) · j +V_(C−DAI,c,m) ^(DL) − 1}     end if    end if    c = c+1   end if  endwhile  m = m +1 end while if V_(temp2) < V_(temp)  j = j +1 end if ifharq-ACK-SpatialBundlingPUCCH is not provided to the UE and the UE isconfigured by maxNrofCodeWordsScheduledByDCI with reception of twotransport blocks for at least one configured DL BWP of a serving cell,       O^(ACK) = 2 · (T_(D) · j + V_(temp2)) else        O^(ACK) = T_(D)· j + V_(temp2) end if

In this case, using the pseudo code of Table 6, the UE may compareV_(temp) and V_(C-DAI,c,m) values as illustrated in (a) of FIG. 13 todetermine whether PDSCH reception is omitted due to failure of receptionof the PDCCH (or DCI) for scheduling of the PDSCH transmitted from thebase station.

For example, as illustrated in (a) of FIG. 13 , when the UE receives the2-bit counter-DAI configuration, the UE may calculate T_(D)=2²=4 and seethat the range that may be expressed as the number of bits of thecounter-DAI is from 1 to 4. When one PDCCH (or DCI) is received, it maybe recognized that the PDSCH is continuously transmitted without missingwhen the value V_(C-DAI,c,m) of the counter-DAI of the PDCCH (or DCI) is‘1’ and the value of V_(temp) is ‘4’. However, when receiving one PDCCH(or DCI), the UE may recognize that the PDSCH scheduled by the PDCCH (orDCI) with the value of counter-DAI of ‘1’ is missed when the valueV_(C-DAI,c,m) of the counter-DAI of the PDCCH (or DCI) is ‘2’ and thevalue of V_(temp) is ‘4’, and may indicate the HARQ-ACK for this PDSCHas NACK.

Furthermore, as illustrated in (b) of FIG. 13 , the UE may recognize theomission of transmission of the PDSCH scheduled by the PDCCH of the basestation by comparing the stored values of V_(temp2) and V_(temp), whichare the stored total-DAI values. For example, as illustrated in (b) ofFIG. 13 , when the UE receives the 2-bit total-DCI configuration,T_(D)=2²=4 is calculated and the range that may be expressed in thenumber of bits of the total-DAI is 1 to 4. When the value of thetotal-DAI V_(temp2) of the PDCCH (or DCI) last received by the UE is ‘1’and the value of V_(temp) is ‘4’, it may be recognized that the PDSCHhas not been missed since the last received PDCCH. However, when thetotal-DAI value V_(temp2) of the PDCCH (or DCI) last received by the UEis ‘2’ and the value of V_(temp) is ‘4’, the UE may recognize that thePDSCH scheduled by one PDCCH (or DCI) has been missed since the lastreceived PDCCH, and may indicate the HARQ-ACK for this PDSCH as NACK.

In Table 6, the size of the UE's final HARQ-ACK codebook may bedetermined by a value of O^(ACK)

A new DCI format for providing ultra-reliable and low-latencycommunication (URLLC) services may be introduced. This new DCI formathas a feature that is capable of setting the length of each field of DCIin order to reduce the bit size. Hereinafter, the newly introduced DCIformat will be referred to as DCI format 0_2 and DCI format 1_2.

DCI format 0_2 is a DCI format for scheduling of a PUSCH, and DCI format1_2 is a DCI format for scheduling of a PDSCH.

In addition, in Rel-16 NR, up to two HARQ-ACK codebooks may be generatedaccording to the service type. For example, one HARQ-ACK codebook may begenerated by collecting HARQ-ACK information about PDSCHs for eMBBservice, and one HARQ-ACK codebook may be generated by collectingHARQ-ACK information about PDSCHs for URLLC service. In DCI formats 1_0,1_1, and 1_2 for scheduling of PDSCH, it needs to be indicated in whichHARQ-ACK codebook HARQ-ACK information about the scheduled PDSCH isincluded. In this case, various methods may be used as a method forindicating HARQ-ACK information.

For example, by adding a separate 1-bit field to the DCI format, index 1may indicate HARQ-ACK for a PDSCH having a high priority such as theURLLC service, and index 0 may indicate HARQ-ACK for a PDSCH having alow priority such as the eMBB service.

Alternatively, the HARQ-ACK of the PDSCH for URLLC and the HARQ-ACK ofthe PDSCH for eMBB may be distinguished by the following parametersand/or methods.

-   -   The HARQ-ACKs may be distinguished by different RNTIs. That is,        based on different RNTIs of the PDCCH (or DCI) for scheduling of        the PDSCH of the URLLC and the PDCCH (or DCI) for scheduling of        the PDSCH of the eMBB, the UE may generate the HARQ-ACK codebook        by distinguishing between the HARQ-ACK of the PDSCH for the        URLLC and the HARQ-ACK of the PDSCH for the eMBB.    -   The HARQ-ACKs may be distinguished according to a CORESET in        which the PDCCH is transmitted. That is, based on the CORESET in        which the PDSCH of the URLLC is transmitted and the CORESET in        which the PDSCH of the eMBB is transmitted, the UE may generate        the HARQ-ACK codebook by distinguishing between the HARQ-ACK of        the PDSCH for the URLLC and the HARQ-ACK of the PDSCH for the        eMBB.    -   The HARQ-ACKs may be distinguished according to the DCI format.        That is, based on the DCI format for scheduling of the PDSCH of        the URLLC and the DCI format for scheduling of the PDSCH of the        eMBB, the UE may generate the HARQ-ACK codebook by        distinguishing between the HARQ-ACK of the PDSCH for the URLLC        and the HARQ-ACK of the PDSCH for the eMBB. For example, DCI        format 0_0 or DCI format 10 always schedules a PUSCH or a PDSCH        having a low priority. In addition, DCI format 0_1 or DCI format        1_1 always schedules a PUSCH or a PDSCH having a low priority.        In addition, DCI format 0_2 or DCI format 1_2 always schedules        the PUSCH or the PDSCH having a high priority.

Based on the methods described above, the UE may know the priority ofeach PDSCH transmitted from the base station, and may generate theHARQ-ACK codebook by collecting HARQ-ACKs of PDSCHs corresponding to thesame priority. Hereinafter, the HARQ-ACK codebook described in thepresent disclosure refer to a HARQ-ACK codebook for HARQ-ACKs of PDSCHscorresponding to the same priority, unless otherwise stated.

FIG. 14 illustrates an example of a method for transmitting a HARQ-ACKbased on downlink control information having a different formataccording to an embodiment of the present disclosure.

The DAI received from the PDCCH (or DCI) includes the counter-DAI andthe total-DAI, and the counter-DAI and the total-DAI may be eachconfigured with a maximum of 2 bits. However, in DCI format 10, thenumber of bits of the counter-DAI is fixed to 2 bits, and in DCI format11, the number of bits of the counter-DAI may be set to be fixed to 2bits and the number of bits of the total-DAI may be set to be fixed to 2bits.

The length of each DCI field of DCI format 1_2 and DCI format 0_2 forthe UE may be set by the base station. For example, the base station mayset the length of the DAI field for generating the HARQ-ACK codebook inDCI format 1_2. In DCI format 1_2, the length of the DAI field may beset to be one of 0 bits, 1 bit, 2 bits, or 4 bits. If the length of theDAI field is set to be 1 bit or 2 bits, the counter-DAI is 1 bit or 2bits and total-DAI is 0 bits. If the length of the DAI field is set tobe 4 bits, the counter-DAI is 2 bits and the total-DAI is 2 bits.

Referring to FIG. 14 , a PDSCH corresponding to one HARQ-ACK codebook ofone UE may be scheduled according to DCI format 1_0, DCI format 1_1, orDCI format 1_2. That is, the DCI formats of the PDSCH corresponding toone HARQ-ACK codebook may have counter-DAI bit-sizes of differentlengths. Hereinafter, when DCI formats have counter-DAI bit-sizes ofdifferent lengths, a method for generating the HARQ-ACK codebook will bedescribed.

FIG. 15(a) and FIG. 15(b) illustrate another example of a method fortransmitting a HARQ-Ack based on downlink control information having adifferent format according to an embodiment of the present disclosure.

Referring to FIG. 15(a) and FIG. 15(b), the UE may generate a HARQ-ACKcodebook for a PDSCH scheduled by each PDCCH having a different DCIformat and transmit it to the base station.

Specifically, as described above, when the DCI format is changed, thenumber of bits of the DAI field included in each piece of DCI may alsovary. In this case, the UE may generate a HARQ-ACK codebook including aHARQ-ACK bit of the PDSCH scheduled by the PDCCH (or DCI) of the DAIfield having a different number of bits and transmit it to the basestation.

In this case, it is difficult for the UE to count the received DAI,since the number of bits of the DAI field is different. That is, whenthe bit value of the DAI field of the first PDCCH (or DCI) is “0” andthe bit value of the DAI field of the second DCI is “11”, it isdifficult for the UE to determine whether the two received PDSCHs arecontinuously transmitted.

Accordingly, when the number of bits of the counter-DAI of each of thereceived PDCCHs (or DCIs) is different, the UE may recognize the orderof the received PDSCH by matching the number of bits of the counter-DAIto be the same. That is, the UE may match the numbers of bits byrecognizing that only some of the bits of the counter-DAI with a largernumber of bits are valid bits, and may match the numbers of bits byextending and interpreting the bits of the counter-DAI with a smallernumber of bits.

Proposal 1: Generating a HARQ-ACK codebook by recognizing only some ofthe bits of counter-DAI as valid bits.

When the numbers of bits of counter-DAI fields of the DCI formatmonitored by the UE are different, only some of the bits of thecounter-DAI having a larger number of bits are recognized as valid bitsto generate the HARQ-ACK codebook. In this case, the number of validbits is equal to the number of bits of the DAI field with a smallernumber of bits among the DAI fields of the received PDCCH (or DCI). Inaddition, in DCI format 1_0 and DCI format 11, the number of bits of thecounter-DAI may be fixed to 2 bits, and in DCI format 1_2, the number ofbits of the counter-DAI may be set to be 0 bits, 1 bit, or 2 bits, andthus the DAI field with a smaller number of bits among the DAI fieldshas the same number of bits as the number of bits of the counter-DAIincluded in DCI format 1_2. That is, when the UE is configured tomonitor DCI format 1_2, the UE may recognize that the number of bits ofthe counter-DAI of DCI format 1_2 is the number of valid bits, and mayrecognize that among the 2-bit counter-DAI of DCI format 1_0 or DCIformat 1_1, only the valid number of bits are valid bits for thecounter-DAI.

Specifically, when the bit size of the counter-DAI of DCI format 1_2 isset to be the N_(C-DAI) bit, only the N_(C-DAI) bit(s) may be determinedas being valid among the 2 bits of the counter-DAI fields of DCI format1_0 and DCI format 1_1, which are other formats of DCI. In this case,the bit(s) determined as being valid may be the LSB N_(C-DAI) bit(s) orthe MSB NCDAI bit(s).

In addition, the counter-DAI value may be determined according to thevalue of the N_(C-DAI) bit(s). For example, when the value of N_(C-DAI)is ‘1’, the number of the valid bits is 1. In this case, when the binaryvalue of the valid bit is 0, the counter-DAI value is 1, and when thebinary value of the valid bit is 1, the counter-DAI value is 2.

When the value of NC-DAI is ‘2’, the number of valid bits is 2. In thiscase, when the binary value of the valid bits is 00, the counter-DAIvalue is 1, and when the binary value is 01, the counter-DAI value is 2.Furthermore, when the binary value is 10, the counter-DAI value is 3,and when the binary value is 11, the counter-DAI value is 4.

For example, when NC-DAI, which is the bit-size of the counter-DAI ofDCI format 1_2, is configured to be 1 bit as illustrated in (a) of FIG.15 , the UE may recognize that only 1 bit of the LSB or MSB among 2 bitsof the counter-DAIs of DCI format 1_0 and DCI format 1_1 is the numberof valid bits of the counter-DAI.

That is, among the numbers of bits of the counter-DAI fields of thereceived DCI, the number of bits of the counter-DAI field with thesmallest number of bits is determined as the number of valid bits, andby recognizing that only some bits of the LSB or MSB are valid among thebits of the counter-DAI fields of the remaining DCI, the bit sizes ofthe counter-DAIs of the received pieces of DCI may be identicallymatched.

The UE may generate the HARQ-ACK codebook using only the valid N_(C-DAI)bit in the counter-DAI field of each DCI format. For example, (a) ofFIG. 15 illustrates a binary value of counter-DAI when the value ofN_(C-DAI), which is a valid bit-size of counter-DAI of DCI format 1_2,is set to be 1 bit.

As illustrated in (a) of FIG. 15 , the counter-DAI of DCI_format 1_1 mayhave binary values of 00, 01, 10, and 11 in 2 bits, but only 1 bit,which is the LSB, may be valid. Invalid binary values are marked with x.In the same monitoring occasion, the counter-DAI value may beincremented by one according to the ascending order of the cell index.

Specifically, the value of counter-DAI is a value determined accordingto the number of PDCCHs transmitted up to the current cell of thecurrent monitoring occasion. If X PDCCHs have been transmitted so far(X-1 mod 2{circumflex over ( )}N_(c-DAI)), the counter-DAI value isdetermined as +1. The UE may determine whether there is a PDCCH that hasfailed to be received by using the value of the counter-DAI.

When the format of the received DCI is DCI format 1_1 and the format ofthe subsequently received DCI is format 1_1, the UE may set the validbit of the counter-DAI to be 1 bit. In this case, only the MSB or LSB ofthe counter-DAI field of DCI format 1_1 may be recognized as a validbit, and the invalid bit of the counter-DAI is not used to calculate thevalue of the counter-DAI.

For example, when the number N_(C-DAI) of bits of the counter-DAI of DCIformat 1_2 received as illustrated in (a) of FIG. 15 is 1 bit, the UEmay determine that the number of valid bits is 1 bit, and even if thenumber of bits of the counter-DAI of DCI format 1_1 is set to be 2 bits,only 1 MSB or LSB among the 2 bits may be used to determine thecounter-DAI value. Accordingly, the invalid 1 bit marked with ‘x’ in (a)of FIG. 15 is not used to determine the counter-DAI value.

If the bit of counter-DAI of DCI format 1_2 is ‘0’, the value ofcounter-DAI may be determined as 1. In this case, when 2 bits of thecounter-DAI of DCI format 1_1 transmitted next are ‘1_1’ or ‘01’, the UEmay determine the value of the counter-DAI by using only ‘1’, which isthe value of the LSB, which is a valid bit. Therefore, the value of thecounter-DAI of DCI format 1_1 may be recognized as 2.

Additionally, Proposal 1 may be interpreted as follows. When the bits ofthe 2-bit counter-DAI of DCI format 1_0 or DCI format 1_1 are ‘00’, theUE determines the value of the counter-DAI as 1, and when ‘01’,determines the value of the counter-DAI as 2, when ‘10’, determines thevalue of counter-DAI as 3, and when ‘11’, determines the value ofcounter-DAI as 4.

When the UE receives a configuration in which the number of bits of thecounter-DAI of DCI format 1_2 is 1 bit, the UE may determine the valueof the counter-DAI as 1 or 2. Here, when the value of the 2-bitcounter-DAI is C₂, C₂ has one of 1, 2, 3, and 4. When the value of 1-bitcounter-DAI is C₁, C₁ has one of 1 and 2.

In this case, the value C₂ of the 2-bit counter-DAI may be convertedinto the same bit value as the value C₁ of the 1-bit counter-DAI throughC₁=(C₂−1) mod 2+1. This method has the same effect as determining that 1bit of the LSB is valid and interpreting the 1 LSB as the 1-bitcounter-DAI value in Proposal 1.

When the counter-DAI value of the previously received PDCCH (or DCI) is1 and the counter-DAI value of the subsequently received PDCCH (or DCI)is 1, the UE may recognize that the two PDCCHs are not transmittedconsecutively, and that at least one PDCCH has been transmitted betweenthe two PDCCHs, but the UE does not receive it.

However, when the reception of two consecutive PDCCHs fails, the UE maynot recognize it. That is, when the N_(C-DAI) is set to be 1 bit, it ispossible to detect a reception failure of at most one PDCCH, but it isnot possible to detect a reception failure of two or more consecutivePDCCHs.

As described above, in DCI formats 1_0 and 1_1, counter-DAI is fixed to2 bits. Therefore, in DCI formats 1_0 and 1_1, the counter-DAI where thenumber of bits is 2 may detect a reception failure of up to threeconsecutive PDCCHs. However, the PDCCH reception failure detectionperformance may be degraded by setting the number of valid bits to be 1bit, which is the number of bits of the counter-DAI of DCI format 1_2according to Proposal 1.

Proposal 2: Generating a HARQ-ACK codebook based on the greatest numberof bits among bits of the counter-DAI.

In the case of Proposal 1, as described above, since the number of validbits of the counter-DAI is only 1 bit, it is not possible to recognizethat two or more consecutive PDCCHs are not detected. Therefore, it maynot be easy to detect the reception failure of the PDCCH.

In order to solve the problem, when the number of bits of thecounter-DAI varies depending on the format of DCI, the value ofcounter-DAI may be determined by extending and interpreting the numberof bits of the counter-DAI based on the number of more bits.

Specifically, when the counter-DAI of DCI format 1_2 is configured withthe N_(C-DAI) bit in bit-size, the N_(C-DAI)-bit counter-DAI is extendedand interpreted as the 2-bit counter-DAI value. In addition, it may bedetermined that the 2-bit counter-DAI for DCI format 1_0 and DCI format1_1 is valid.

For example, as illustrated in (b) of FIG. 15 , DCI format 1_0 and DCIformat 1_1 include a two-bit counter-DAI, and thus, when bits of thecounter-DAI are ‘00’ in binary number, the counter-DAI value may be 1,and when the bits are ‘01’ in binary number, the counter-DAI value maybe 2. In addition, when the bits of the counter-DAI are 10 in binarynumber, the counter-DAI value may be 3, and when the bits of thecounter-DAI are 11 in binary number, the counter-DAI value may be 4.

In this case, when the value of N_(C-DAI), which is the bit size of thecounter-DAI of DCI format 1_2, is 1 bit, the UE may extend and interpretthe number of bits of the counter-DAI of DCI format 1_2 as 2 bits. Forexample, when 1 bit of counter-DAI of DCI format 1_2 is extended andinterpreted as 2 bits when it is ‘0’, the counter-DAI may have a bitvalue of ‘00’ or ‘10’. Therefore, the counter-DAI value may be extendedand interpreted as 1 or 3.

Alternatively, when 1 bit of counter-DAI of DCI format 1_2 is extendedand interpreted as 2 bits when it is ‘1’, the counter-DAI may have a bitvalue of ‘01’ or ‘11’. Therefore, the counter-DAI value may be extendedand interpreted as 2 or 4.

When the counter-DAI with a 1-bit size of DCI format 1_2 is extended andinterpreted as 2 bits by Proposal 2, the value of the counter-DAI mayhave two or more candidate values by the extended interpretation. Inthis case, the UE may recognize that the value with the smallest numberof non-consecutive PDCCHs is the value of the counter-DAI. That is, wheninterpreted by extending the number of bits of the counter-DAI, the UEmay determine the value corresponding to the value with the smallestnumber of undetected PDCCHs as the value of the counter-DAI.

For example, when the value of the 2-bit counter-DAI of the previouslyreceived DCI is 3 and the bit of the 1-bit counter-DAI of thesubsequently received PDCCH (or DCI) is ‘1’, the UE may determine, asthe counter-DAI, the value 4, which is the value with the smallestnumber of undetected PDCCHs out of the candidate value 2 or 4 that maybe the value of the counter-DAI, by extending and interpreting the 1-bitcounter-DAI as 2 bits. In other words, when a determination is made thatthe counter-DAI of the subsequently received PDCCH (or DCI) is 2, adetermination is made that the receptions of two PDCCHs (or DCIs) withthe counter-DAI values of 4 and 1 have failed. However, when adetermination is made that the counter-DAI of the received PDCCH (orDCI) is 4, the UE determines that there is no PDCCH (or DCI) that hasfailed to be received. When the probability that the UE fails to receivethe PDCCH is p, the probability of determining that the counter-DAI is 2and that the reception of two consecutive PDCCHs (or DCIs) fails is p²,and the probability determining that the counter-DAI is 4 and that thereis no PDCCH (or DCI) reception failure is 1-p. In general, p is a verysmall value for the base station to allow the UE to successfully receivethe PDCCH (or DCI). Therefore, counter-DAI 4 with probability 1-p occursmore frequently than counter-DAI 2 with probability p². Therefore, inthe above case, the value of the counter-DAI is more likely to be 4 than2, and thus it is desirable to determine the counter-DAI as 4.

Table 7 below shows an example of values of the counter-DAI extended andinterpreted for the counter-DAI of the previously received DCI when thebit of the counter-DAI is extended and interpreted. Here, thecounter-DAI is 1 bit, and the value of the counter-DAI of the previouslyreceived DCI is 2 bits.

TABLE 7 V_(temp) Counter-DAI 1(00) 2(01) 3(10) 4(11) 1 or 3(0) 3 3 1 1 2or 4(1) 2 4 4 2

In Table 7, the number in parentheses means each bit value.

For another example of Proposal 2, DCI format 1_0 and DCI format 1_1include a two-bit counter-DAI, and thus, when bits of the counter-DAIare ‘00’ in binary number, the counter-DAI value may be 1, and when thebits are ‘01’ in binary number, the counter-DAI value may be 2. Inaddition, when the bits of the counter-DAI are 10 in binary number, thecounter-DAI value may be 3, and when the bits of the counter-DAI are 11in binary number, the counter-DAI value may be 4.

In this case, when the value of N_(C-DAI), which is the bit size of thecounter-DAI of DCI format 1_2, is 0 bits, the UE may extend andinterpret the number of bits of the counter-DAI of DCI format 1_2 as 2bits. In this case, since the size of the counter-DAI is 0 bits, when itis extended and interpreted as 2 bits, the counter-DAI of 0 bits mayhave four candidate values.

When the counter-DAI value is extended and interpreted as a value withthe smallest number of undetected PDCCHs out of the four candidatevalues, the UE may determine the counter-DAI value as a valueconsecutive to the counter-DAI value of the previously received DCI.

Table 8 below shows an example of the counter-DAI values extended andinterpreted for the counter-DAI of the previously received DCI when thebit of the counter-DAI is extended and interpreted. Here, thecounter-DAI is 0 bits, and the value of the counter-DAI of thepreviously received DCI is 2 bits.

TABLE 8 V_(temp) Counter-DAI 1(00) 2(01) 3(10) 4(11) Empty 1 2 3 4

That is, when the bit size of the counter-DAI of DCI format 1_2 is lessthan 2 bits, there may be a plurality of possible 2-bit counter-DAIvalues. The UE may select one value from among a plurality of possible2-bit counter-DAI values.

In order to select one of the plurality of candidate values, thefollowing specific method may be used.

When the counter-DAI value of the PDCCH received immediately before is Cand the currently received counter-DAI of DCI format 1_2 is interpretedas 2 bits, it is assumed that the possible 2-bit counter-DAI values arei1, i2, . . . . . The UE needs to determine one value of the i1, i2, asthe 2-bit counter-DAI value by using the V_(temp) or C value.

The UE may calculate a value of Y based on Equation 2 below in the orderof x=1, 2, 3.

Y=((V _(temp) or C)+x−1 mod 4)+1  [Equation 2]

If Y is one value of i1, i2, . . . , the UE determines that the value ofthe 2-bit counter-DAI is Y This is a method for setting the 2-bitcounter-DAI value to minimize the number of PDCCHs that have failed tobe received since the immediately previously received PDCCH until theDCI format 1_2 currently received.

In Tables 4 and 5, V_(temp) is a value (when the previously lastreceived DCI format is DCI format 1_2, a value interpreted as the 2-bitcounter-DAI value) of the counter-DAI with a 2-bit size immediatelybefore (that is, the cell with a low cell index in the currentmonitoring occasion or the PDCCH last received in the previousmonitoring occasion).

For example, when the value of V_(temp) is 1 and the currently receivedcounter-DAI of DCI format 1_2 is 0 in binary number, the counter-DAI mayhave a value of 1 or 3. When it is determined that the counter-DAI valueis 3, it indicates a case where one PDCCH (the counter-DAI value is 2)has been transmitted between the previously received PDCCH (thecounter-DAI value is 1) and the currently received PDCCH (thecounter-DAI value is 3), but reception thereof has failed. When it isdetermined that the counter-DAI value is 1, it indicates a case wherethree PDCCHs (the counter-DAI values are 2, 3, and 4) have beentransmitted between the previously received PDCCH (the counter-DAI valueis 1) and the currently received PDCCH (the counter-DAI value is 1), butreceptions thereof have failed. It is assumed that the smallest numberof PDCCHs has been transmitted according to the previous embodiment butreception thereof has failed, and it may be determined that the value ofthe counter-DAI of the currently received PDCCH is 3.

In Proposals 1 and 2, only counter-DAI is used when generating theHARQ-ACK codebook, but the HARQ-ACK codebook may be generated byadditionally using the total-DAI value. For example, in DCI format 1_2,total-DAI may be configured with the NT-DAI bits. In this case, similarto the method of Proposal 1, only the LSB (or MSB) N_(T-DAI) bits in thetwo bit total-DAI field of DCI format 1_1 including the 2-bit total-DAIfield are determined as valid bits, and the total-DAI value may bedetermined based on the valid N_(T-DAI) bits.

In another embodiment of the present disclosure, a HARQ-ACK codebook maybe generated by using a 2-bit total-DAI value. The Total-DAI value isdetermined according to the number of PDCCHs received up to the currentmonitoring occasion. If the number of PDCCHs received up to the currentmonitoring occasion is T, the total-DAI of the N_(T-DAI) bit may bedetermined as ((T−1) mod 2{circumflex over ( )}N_(T-DAI))+1. The PDCCHreceived in one monitoring occasion has the same 2-bit total-DAI value.

In another embodiment of the present disclosure, when at least one DCIformat 1_1 is received in one monitoring occasion, a 2-bit total-DAIvalue included in DCI format 1_1 may be used. That is, when DCI formatincluding the 2-bit total-DAI and DCI format including 1-bit total-DAIor 0-bit total-DAI are received in the same monitoring occasion, the2-bit total-DAI contains the most information, and thus the 2-bittotal-DAI value may be assumed.

In another embodiment of the present disclosure, when DCI format 1_1 isnot received and DCI format 1_2 is received in one monitoring occasion,the value of 2-bit total-DAI may be determined as follows.

When the value of NT-DAI, which is the bit size of total-DAI in DCIformat 1_2, is 1 bit, it may be expanded and interpreted as a 2-bittotal-DAI value. For example, when the bit of the 1-bit total-DAI is‘0’, the total-DAI value may be 1 or 3, and when the bit is ‘1’, thetotal-DAI value may be 2 or 4.

When the value of NT-DAI, which is the bit size of total-DAI in DCIformat 1_2, is 0 bits (that is, when the total-DAI is not included inDCI format), the 0-bit total-DAI may be interpreted as a 2-bit total-DAIvalue.

For example, the value of 0 bit total-DAI may be 1, 2, 3 or 4. That is,when the bit size of the total-DAI of DCI format 1_2 is less than 2bits, the 2-bit total-DAI may have a plurality of candidate values. Inthis case, one value may be selected from among the plurality ofcandidate values through the following method.

The value of the 2-bit counter-DAI of the PDCCH last received (that is,received from the cell with the highest cell index) in the currentmonitoring occasion may be C, and the value of the 2-bit total-DAI thatthe total-DAI included in the DCI on the PDCCH received in thecorresponding monitoring occasion may have may be j1, j2,

In this case, the UE needs to determine one value of j1, j2, as the2-bit total-DAI value by using the C value. The UE may calculate thevalue of Z based on Equation 3 below in turn according to the value of x(x=0, 1, 2, 3, . . . ).

Z=((V _(temp) or C)+x−1 mod 4)+1  [Equation 3]

If Z is one value of the values j1, j2, the UE determines that the valueof the 2-bit total-DAI is Z. This is a method for setting the value ofthe 2-bit total-DAI to minimize the number of PDCCHs that have failed tobe received for PDCCH that has been transmitted since the last PDCCH ofthe current monitoring occasion.

Table 9 below is a table showing an example of a total-DAI valueselected from among a plurality of candidate values.

TABLE 9 V_(temp2) Total-DAI 1(00) 2(01) 3(10) 4(11) 1 or 3(0) 1 3 3 1 2or 4(1) 2 2 4 4

In Table 9, V_(temp2) is a value of the 2-bit counter-DAI of the lastPDCCH among the PDCCHs received in the monitoring occasion. For example,when the value of the previous V_(temp2) is 2 and the currently receivedcounter-DAI of DCI format 1_2 is 0 in binary number, the total-DAI mayhave 1 or 3.

When it is determined that the total-DAI value is 3, it indicates a casewhere one PDCCH (the counter-DAI value is 3) has been transmitted sincethe last received PDCCH (the counter-DAI value is 2), but the UE doesnot detect it. When it is determined that the total-DAI value is 1, itindicates a case where three PDCCHs (the counter-DAI values are 3, 4,and 1) have been transmitted since the last received PDCCH (thecounter-DAI value is 2), but the UE does not detect them. It is assumedthat the smallest number of PDCCHs has been transmitted according to theprevious embodiment but receptions thereof have failed, and it may bedetermined that the value of the total-DAI of the received PDCCH is 3.

Through the method described above, the UE may determine the number ofvalid bits or extend and interpret the number of bits even when thenumber of bits of the counter-DAI or total-DAI of DCI having a differentformat is different, and multiplex the HARQ-ACK codebook for the PDSCHsscheduled by a plurality of pieces of DCI and transmit it to the basestation.

FIG. 16 illustrates an example of a method for transmitting a HARQ-Ackbased on downlink control information for uplink and downlink schedulingaccording to an embodiment of the present disclosure.

Referring to FIG. 16 , the UE multiplexes the PUSCH scheduled throughthe DCI and the HARQ-ACK codebook including the HARQ-ACK bits of thePDSCH scheduled through the DCI on the PDCCH and transmits them to thebase station.

Specifically, as illustrated in FIG. 16 , the UE may multiplex (orpiggyback) the HARQ-ACK bits of the received PDSCHs with the PUSCH andtransmit them to the base station. In this case, the DCI formats forscheduling of PDSCHs are DCI format 10, DCI format 1_1, and/or DCIformat 1_2. In addition, the DCI formats for scheduling of the PUSCHwith which HARQ-ACK bits are multiplexed (or piggybacked) includes DCIformat 0_0, DCI format 0_1, DCI format 0_2, and/or the like.

The length of the UL DAI field included in DCI format 0_2 may be set tobe 0, 1, or 2 bits. Furthermore, the length of the counter-DAI fieldincluded in DCI format 1_2 may be set to be 0, 1, or 2 bits.

In addition, DCI format 0_0 and DCI format 0_1 may include a 2-bit ULDAI field, and DCI format 1_0 and DCI format 1_1 may include a 2-bitcounter-DAI field.

In this case, when the length of the UL DAI field is not the same as thelength of the counter-DAI field of DCI format 1_2, it is necessary todetermine the value of the UL DAI field based on the counter-DAI field.Hereinafter, in the embodiment, it is assumed that the length of the DAIfield is not at least 0. That is, the DCI format may include a DAI fieldhaving a length of at least 1 bit.

In a first embodiment, when the length of the UL DAI field is greaterthan the length of the counter-DAI field of DCI format 1_2 (e.g., whenthe length of the UL DAI field is 2 bits and the length of thecounter-DAI field is 1 bit), the UE may determine only some of the bitsof the UL DAI field as valid bits of the UL DAI field. Here, the numberof some bits has the same number as that of bits of the counter-DAIfield, and may be bits closest to the MSB or LSB of the UL DAI field.

The UE may calculate the UL DAI value by using bits determined as validbits among the bits of the UL DAI field. If the UL DAI field has onevalid bit, the UL DAI value is 1 when the bit is ‘0’, and the UL DAIvalue is 2 when it is 1.

If the UL DAI field has two valid bits, the UL DAI value is 1 when thebits are ‘00’, and the UL DAI value is 2 when they are 01. In addition,the UL DAI value is 3 when the 2 bits is 10, and the UL DAI value is 4when the 2 bits are 11.

The UE may use the UL DAI value obtained using the bits of the UL DAIfield determined as valid and the counter-DAI value obtained from thecounter-DAI field to determine the number of HARQ-ACK bits for PDSCHsthat have not been received.

For example, let the UL DAI value be X and the counter-DAI value be Y IfX=Y, it may be determined that there is no PDSCH that has not beenreceived. However, when Y<X, it may be determined that X-Y PDSCHs havenot been received, and when X<Y, it may be determined that T-(Y-X)PDSCHs have not been received. Here, T=2^(N) and N is the number of bitsof the counter-DAI field.

In a second embodiment, when the length of the UL DAI field is greaterthan the length of the counter-DAI field of DCI format 1_2 (e.g., thelength of the UL DAI field is 2 bits and the length of the counter-DAIfield is 1 bit), the UE may first determine the UL DAI value accordingto the length of the UL DAI field, and then modify the determined UL DAIvalue according to the counter-DAI field, thereby determining the finalUL DAI value.

The process of first determining the value of the UL DAI according tothe length of the UL DAI field is as follows. If the UL DAI field hasafield length of 1 bit, the UL DAI value is 1 when the bit value is ‘0’,and the UL DAI value is 2 when the bit value is ‘1’.

If the UL DAI field has a field length of 2 bits, the UL DAI value is 1when the bit value is ‘00’, and the UL DAI value is 2 when the bit valueis ‘01’. In addition, the UL DAI value is 3 when the bit value is ‘10’,and the UL DAI value is 4 when the bit value is ‘11’.

When the UL DAI value is determined according to the UL DAI field, theUE may modify the determined UL DAI value to match the counter-DAI fieldto determine the final UL DAI value as follows.

When T=2^(N), where N is the number of bits of the counter-DAI field,and the determined value of the UL DAI is Z, the final UL DAI value (X)may be calculated using Equation 4 below.

Final UL DAI value(X)=((Z−1)mod T)+1  [Equation 4]

The UE may use the final UL DAI value X and the counter-DAI valueobtained from the counter-DAI field to determine the number of HARQ-ACKbits for PDSCHs that have not been received. For example, when thecounter-DAI value is Y, it may be determined that there is no PDSCH thathas not been received when X=Y However, when Y<X, it may be determinedthat X-Y PDSCHs have not been received, and when X<Y, it may bedetermined that T-(Y-X) PDSCHs have not been received. Here, T=₂N and Nis the number of bits of the counter-DAI field.

In a third embodiment, when the length of the UL DAI field is greaterthan the length of the counter-DAI field of DCI format 1_2 (e.g., thelength of the UL DAI field is 2 bits and the length of the counter-DAIfield is 1 bit), the UE may assume (or recognize) that the range of theUL DAI values is the same as the range of the values that thecounter-DAI may indicate. For example, when a value that may beindicated by the counter-DAI is 1, 2, 3, or 4, the value of the UL DAImay be recognized as one of 1, 2, 3, and 4.

Specifically, the UE may determine the value of the UL DAI according tothe length of the UL DAI field. If the UL DAI field has a field lengthof 1 bit, the UL DAI value is 1 when the bit value is ‘0’, and the ULDAI value is 2 when the bit value is ‘1’. If the UL DAI field has afield length of 2 bits, the UL DAI value is 1 when the bit value is‘00’, and the UL DAI value is 2 when the bit value is ‘01’. In addition,the UL DAI value is 3 when the bit value of the 2 bits is ‘10’, and theUL DAI value is 4 when the bit value is ‘11’.

The UL DAI value always needs to be within the range of values that thecounter-DAI may indicate. For example, when the UL DAI field has alength of 2 bits, the range of the UL DAI values is 1, 2, 3, and 4. Ifthe counter-DAI value may have a range of 1 and 2, the length of the ULDAI field is 2 bits, but the values that the UL DAI may have are 1 and2.

That is, the UE does not expect to be instructed with a UL DAI valueindicating a value out of the range of values that the counter-DAI mayhave. It is not expected that 10 or 11, in which the value of the UL DAIindicates 3 or 4, is to be indicated. That is, when this value isindicated, the UE may determine an error case.

As described above, in DCI format 0_2, the length of the UL DAI fieldmay be set to be 0, 1, or 2 bits. When the length of the UL DAI field isless than 2 bits, for the UL DAI, the 2-bit UL DAI value may bedetermined in the same way as the method for determining the 2-bittotal-DAI value.

That is, the value of the UL DAI may be determined by using the lastreceived 2-bit counter-DAI value. Table 10 below is a table showing anexample of the 2-bit UL-DAI value.

TABLE 10 V_(temp3) UL DAI 1(00) 2(01) 3(10) 4(11) 1 or 3(0) 1 3 3 1 2 or4(1) 2 2 4 4

In Table 10, V_(temp3) is a 2-bit counter-DAI value of the last PDCCHamong the received PDCCHs. For example, when the value of the previousV_(temp)3 is 2 and the bit value of the received UL-DAI of DCI format0_2 is 0, the UL-DAI value may have 1 or 3.

When the UL-DAI value is determined as 3, it indicates a case where onePDCCH (the counter-DAI value is 3) has been transmitted since the lastreceived PDCCH (the counter-DAI value is 2), but reception thereof hasfailed, and when the UL-DAI value is determined as 1, it indicates acase where three PDCCHs (the counter-DAI values are 3, 4, and 1) havebeen transmitted since the last received PDCCH (the counter-DAI value is2), but receptions thereof have failed. As described above, when it isassumed that the smallest number of PDCCHs has been transmitted butreceptions thereof has failed, the 2-bit UL-DAI value may be determinedas 3.

FIG. 17(a) and FIG. 17(b) illustrate an example of a downlink assignmentindicator of each piece of downlink control information detected in amonitoring occasion according to an embodiment of the presentdisclosure.

In another embodiment of the present disclosure, when the UE has a bitsize of the UL DAI field of DCI format 00, 0_1, or 0_2 different fromthe bit size of the counter-DAI field of DCI format 1_0, 1_1, or DCIformat 1_2, the UE may perform the following operations.

When the bit size of the counter-DAI field of DCI format 10, 1_1, or 1_2is NC-DAI bits, the counter-DAI value may indicate 1, 2, . . . ,2{circumflex over ( )}N_(C-DAI). Here, when the largest value C_(D) is2{circumflex over ( )}N_(C-DAI), that is, when the bit size N_(C-DAI) ofthe counter-DAI field is 2 bits, the counter-DAI value may be 1 when thebit value of the counter-DAI field is ‘00’, 2 when ‘01’, 3 when ‘10’,and 4 when ‘11’. In this case, the value of C_(D) may be 4.

Alternatively, when N_(C-DAI) is 1 bit, the counter-DAI value may be 1when the value of the counter-DAI field is 0, and 2 when 1, where thevalue of C_(D) is 2.

If the UE receives the DCI format for scheduling of the PDSCH in theserving cell c of the monitoring occasion m, and the counter-DAI valueof the received DCI format is V_(C-DAI,c,m), the UE may determine thatCD*j+V_(C-DAI,c,m) DCI formats for scheduling of the PDSCH have beenreceived up to the current serving cell c of the current monitoringoccasion m where the DCI format has been received. Here, j is anon-negative integer.

In other words, when the number of DCI formats for scheduling of thePDSCH is X up to the current serving cell c of the current monitoringoccasion m where the DCI format has been received, the counter-DAI valueof the DCI format is V_(C-DAI,c,m)=(X−1 mod CD)+1.

When the bit size of the UL DAI field of DCI format 00, 01, or 0_2 isN_(UL-DAI) bits, the UL DAI value may be expressed as 1, 2, . . . ,2{circumflex over (N)}_(UL-DAI). Here, when the largest value U_(D) is2{circumflex over ( )}N_(UL-DAI), that is, when the bit size N_(UL-DAI)of the UL DAI field is 2 bits, the UL DAI value is 1 when the bit valueof the UL DAI field is ‘00’, 2 when ‘01’, 3 when ‘10’, and 4 when ‘11’.Further, the value of UD is 4.

If the UE receives the DCI format for scheduling of the PUSCH in themonitoring occasion m, and the UL-DAI value of the received DCI formatis V_(UL-DAI,m), the UE may determine that U_(D)*i+V_(UL-DAI,m) DCIformats for scheduling of the PDSCH up to the current monitoringoccasion m receiving the DCI format have been received. Here, i is anon-negative integer.

In other words, when the number of DCI formats for scheduling of thePDSCH is X up to the current monitoring occasion m where the DCI formathas been received, the UL-DAI value of the DCI format isV_(UL-DAI,m)=(X−1 mod U_(D))+1.

For example, when the value of U_(D) is 4 and the value of C_(D) is 2,the counter-DAI value may be 1 or 2, and the UL-DAI value may be 1, 2,3, or 4. (a) of FIG. 17 illustrates an example of counter-DAI values ofDCI formats received in monitoring occasions (MO) #0 to #6.

According to the definition of the counter-DAI value, the counter-DAIvalue of DCI format received on MO #0 is 1, the counter-DAI value of DCIformat received on MO #1 is 2, the counter-DAI value of the DCI formatreceived on MO #2 is 1, the counter-DAI value of the DCI format receivedon MO #3 is 2, the counter-DAI value of the DCI format received on MO #4is 1, the counter-DAI value of the DCI format received on MO #5 is 2,and the counter-DAI value of the DCI format received on MO #6 is 1.Furthermore, the UE receives the DCI format for scheduling of the PUSCH.The UL DAI value of the received DCI format is 3. This is because sevenDCI formats for scheduling of the PDSCH have been previously received.

In the present disclosure, when the bit size of the counter-DAI and thebit size of the UL DAI are different from each other, a method forgenerating a HARQ-ACK codebook by the UE is presented. It is assumedthat the UE has not received the DCI format of MO #4 and MO #5 in (b) ofFIG. 17 . Since the UE has received the DCI format in which thecounter-DAI value is 2 on MO #3 and the DCI format in which thecounter-DAI value is 1 on MO #6, the UE may not know the receptionfailure of the DCI format on MO #4 and MO #5. Therefore, the UEgenerates only HARQ-ACK bits for DCI formats received on MO #0, MO #1,MO #2, MO #3, and MO #6 and includes them in the HARQ-ACK codebook.

If the UE receives 3 as the UL-DAI value in the DCI format forscheduling of the PUSCH, the UE may recognize that there are two moreDCI formats in addition to the five DCI formats that have beensuccessfully received. Accordingly, the UE may generate HARQ-ACK bits ofa total of seven DCI formats and include them in the HARQ-ACK codebook.

FIG. 19(a) and FIG. 19(b) illustrate an example of a method fortransmitting a HARQ-ACK based on downlink control information having adifferent format based on a pseudo code according to an embodiment ofthe present disclosure.

Referring to FIG. 19(a) and FIG. 19(b), a HARQ-ACK codebook may begenerated by using a UL-DAI value and a counter-DAI value using a pseudocode and transmitted to the base station. FIG. 19(a) and FIG. 19(b)illustrate an example of multiplexing a 2-bit UL-DAI and a 1-bitcounter-DAI.

Specifically, in an embodiment of the present disclosure, the UL-DAIvalue and the counter-DAI value may be used as follows. First, asillustrated in (a) of FIG. 19 , let the counter-DAI value received bythe UE at the last MO be V_(temp). As mentioned earlier, the counter-DAIvalue may have one of 1, 2, . . . , C_(D). Let the UL DAI value receivedby the UE in the DCI format for scheduling of the PUSCH be V_(temp2).The UE generates the HARQ-ACK codebook through the following process.

First, the UE may determine the number of DCI formats W_(temp) forscheduling of the PDSCH with V_(temp). W_(temp) may be determined byEquation 5 below.

W _(temp) =C _(D) *j+V _(temp)  [Equation 5]

In Equation 5, the initial value of j is set to 0, and when thecounter-DAI value of the DCI format for scheduling of the PDSCH on thecurrent MO is smaller than the counter-DAI value of the DCI format forscheduling of the PDSCH on the previous MO, it may be incremented byone. That is, DCI formats having the counter-DAI values of 1, 2, . . . ,C_(D) are grouped into one group, and j indicates how many groups havebeen received. In (b) of FIG. 17 , j=2.

Then, the UE converts the number W_(temp) of the DCI formats forscheduling the PDSCH into V′_(temp), which is a counter-DAI valuecorresponding to N_(UL-DAI), which is the bit size of the UL DAI field,as illustrated in (b) of FIG. 19 . In this case, V′_(temp) may bedetermined by Equation 6 below.

V′ _(temp)=((W _(temp)-1)mod U _(D))+1  [Equation 6]

In Equation 6, V′_(temp) has one of 1, 2, U_(D) like the UL DAI. The UEmay determine the value of j by comparing V′_(temp) and V_(temp2). IfV_(temp2)<V′_(temp), the value of j may be determined through Equation 7below.

$\begin{matrix}{j = {j + \frac{U_{D}}{C_{D}}}} & \left\lbrack {{Equation}7} \right\rbrack\end{matrix}$

Otherwise, j may remain as it is. Using the value of j, the UE maydetermine the size O^(ACK) of the HARQ-ACK codebook. If the UE isconfigured to receive only 1 TB per PDSCH, O^(ACK) may be calculatedthrough Equation 8 below.

$\begin{matrix}{O^{ACK} = {{{U_{D} \cdot {floor}}\left( {j \cdot \frac{C_{D}}{U_{D}}} \right)} + V_{{temp}2}}} & \left\lbrack {{Equation}8} \right\rbrack\end{matrix}$

If the UE is configured to receive 2 TB per PDSCH, ₀a may be calculatedthrough Equation 9 below.

$\begin{matrix}{O^{ACK} = {2\left( {{{U_{D} \cdot {floor}}\left( {j \cdot \frac{C_{D}}{U_{D}}} \right)} + V_{{temp}2}} \right)}} & \left\lbrack {{Equation}9} \right\rbrack\end{matrix}$

When this is expressed in a pseudo code, it is shown as in Table 11below.

TABLE 11 If the UE transmits HARQ-ACK information in a PUCCH in slot nand for any PUCCH format, the UE determines the õ₀ ^(ACK) ,õ₁ ^(ACK),...,õ_(O) _(ACK) ⁻¹ ^(ACK) , for a total number of O_(ACK) HARQ-ACKinformation bits, according to the following pseudo-code:  Set m=0 -PDCCH with DCI format scheduling PDSCH reception or SPS PDSCH releasemonitoring   occasion index: lower index corresponds to earlier PDCCHmonitoring occasion  Set j=0  Set V_(temp)=0  Set V_(temp2)=0  Set V_(s)is an empty set  Set N_(cells) to the number of serving cells configuredby higher layers for the UE  Set M to the number of PDCCH monitoringoccasion(s)  While m<M   Set c=0 - serving cell index: lower indexescorrespond to lower RRC indexes of corresponding cell   whilec<N_(cells)    if PDCCH monitoring occasion m is before an active DL BWPchange on serving cell c or an    active UL BWP change on the PCell andan active DL BWP change is not triggered in PDCCH    monitoring occasionm     c=c+1;    else     if there is a PDSCH on serving cell cassociated with PDCCH in PDCCH monitoring     occasion m, or there is aPDCCH indicating SPS PDSCH release on serving cell c      ifV_(C−DAI,c,m) is less than or equal to V_(temp)       j=j+1      end if     V_(temp)=V_(C−DAI,c,m)      if V_(T−DAI,m) is empty       V_(temp2)= V_(C−DAI,c,m)      else       V_(temp2) = V_(T−DAI,m)      end if     if harq-ACK-SpatialBundlingPUCCH is not provided and the UE isconfigured by      maxNrofCodeWordsScheduledByDCI with reception of twotransport blocks for at least      one configured DL BWP of at least oneserving cell,       ${\overset{\sim}{o}}_{{2 \cdot C_{D} \cdot j} + {2{({V_{{C - {DAI}},c,m}^{DL} - 1})}}}^{ACK} = {{HARQ} - {ACK}}$       information bit corresponding to the first transport block ofthis cell       ${\overset{\sim}{o}}_{{2 \cdot C_{D} \cdot j} + {2{({V_{{C - {DAI}},c,m}^{DL} - 1})}} + 1}^{ACK} = {{HARQ} - {ACK}}$       information bit corresponding to the second transport block ofthis cell V_(s) = V_(s) ∪ {2 · C_(D) · j + 2(V_(C−DAI,c,m) ^(DL) − 1), 2· C_(D) · j + 2(V_(C−DAI,c,m) ^(DL) − 1) + 1}     elseifharq-ACK-SpatialBundlingPUCCH is provided to the UE and m is amonitoring     occasion for PDCCH with a DCI format that supports PDSCHreception with two     transport blocks and the UE is configured bymaxNrofCodeWordsScheduledByDCI with     reception of two transportblocks in at least one configured DL BWP of a serving cell,       ${\overset{\sim}{o}}_{{C_{D} \cdot j} + V_{{C - {DAI}},c,m}^{DL} - 1}^{ACK} = {{binary}{AND}{operation}{of}{the}{HARQ} - {ACK}}$       information bits corresponding to the first and second transportblocks of this cell V_(s) = V_(s) ∪ {C_(D) · j + V_(C−DAI,c,m) ^(DL) −1}     else      ${\overset{\sim}{o}}_{{C_{D} \cdot j} + V_{{C - {DAI}},c,m}^{DL} - 1}^{ACK} = {{HARQ} - {ACK}}$      information bit of this cell V_(s) = V_(s) ∪ {C_(D) · j +V_(C−DAI,c,m) ^(DL) − 1}     end if    end if    c=c+1   end if  endwhile  m=m+1 end while if V_(temp2) < (C_(D) · j + V_(temp) − 1) modU_(D) ) + 1 or V_(temp) = 0   $j = {j + \frac{U_{D}}{C_{D}}}$ end if ifharq-ACK-SpatialBundlingPUCCH is not provided to the UE and the UE isconfigured by maxNrofCodeWordsScheduledByDCI with reception of twotransport blocks for at least one configured DL BWP of a serving cell,$O^{ACK} = {2 \cdot \left( {{U_{D} \cdot {{floor}\left( {j \cdot \frac{C_{D}}{U_{D}}} \right)}} + V_{{temp}2}} \right)}$else  $O^{ACK} = {{U_{D} \cdot {{floor}\left( {j \cdot \frac{C_{D}}{U_{D}}} \right)}} + V_{{temp}2}}$ end if  õ_(i) ^(ACK) = NACK for any i ∈{0,1,...,O^(ACK) − 1}\V_(s)  Setc=0  while c<N_(cells)   if a single SPS PDSCH reception is activatedfor a UE and the UE is configured to receive SPS   PDSCH in a slotn-K_(1,c) for serving cell c, where K_(1,c) is thePDSCH-to-HARQ-feedback timing   value for SPS PDSCH on serving cell c   O^(ACK)=O^(ACK)+1     o_(O^(ACK) − 1)^(ACK) = HARQ − ACK   information bit associated with the SPS PDSCH reception   end if  c=c+1; end while

FIG. 18(a) and FIG. 18(b) illustrate another example of a downlinkassignment indicator of each piece of downlink control informationdetected in a monitoring occasion according to an embodiment of thepresent disclosure.

In another embodiment of the present disclosure, when the UE has a bitsize of the total-DAI field of DCI format 1_0, 1_1, or 1_2 differentfrom the bit size of the counter-DAI field of DCI format 1_0, 1_1, orDCI format 1_2, the UE may generate the HARQ-ACK codebook through thefollowing operations.

When the bit size of the counter-DAI field of DCI format 10, 1_1, or 1_2is N_(C-DAI) bits, the counter-DAI value may indicate 1, 2, . . . ,2{circumflex over ( )}N_(C-DAI). Here, when the largest value C_(D) is2{circumflex over ( )}N_(C-DAI), that is, when the bit size N_(C-DAI) ofthe counter-DAI field is 2 bits, the counter-DAI value may be 1 when thebit value of the counter-DAI field is ‘00’, 2 when ‘01’, 3 when ‘10’,and 4 when ‘11’. In this case, the value of CD may be 4.

Alternatively, when N_(C-DAI) is 1 bit, the counter-DAI value may be 1when the value of the counter-DAI field is 0, and 2 when 1, where thevalue of C_(D)is 2.

If the UE receives the DCI format for scheduling of the PDSCH in theserving cell c of the monitoring occasion m, and the counter-DAI valueof the received DCI format is V_(C-DAI,c,m), the UE may determine thatCD*j+V_(C-DAI,c,m) DCI formats for scheduling of the PDSCH have beenreceived up to the current serving cell c of the current monitoringoccasion m where the DCI format has been received. Here, j is anon-negative integer.

In other words, when the number of DCI formats for scheduling of thePDSCH is X up to the current serving cell c of the current monitoringoccasion m where the DCI format has been received, the counter-DAI valueof the DCI format is V_(C-DAI,c,m)=(X−1 mod CD)+1.

When the bit size of the total-DAI field of DCI format 1_0, 11, or 1_2is N_(T-DAI) bits, the total-DAI value may indicate 1, 2, . . . ,2{circumflex over ( )}N_(T-DAI). Here, when the largest value T_(D) is2{circumflex over ( )}N_(T-DAI), that is, when the bit size N_(T-DAI) ofthe total-DAI field is 2 bits, the total-DAI value is 1 when the bitvalue of the total-DAI field is ‘00’, 2 when ‘01’, 3 when ‘10’, and 4when ‘11’. Further, the value of T_(D) is 4.

If the UE receives the DCI format for scheduling of the PDSCH in themonitoring occasion m, and the total-DAI value of the DCI format isVT-DAI,m, the UE may determine that T_(D)*i+V_(T-DAI,m) DCI formats forscheduling of the PDSCH up to the current monitoring occasion mreceiving the DCI format have been received. Here, i is a non-negativeinteger.

In other words, when the number of DCI formats for scheduling of thePDSCH is X up to the current monitoring occasion m where the DCI formathas been received, the total-DAI value V_(T-DAI,c,m) of the DCI formatis (X−1 mod T_(D))+1.

Let's look at a case where the value of T_(D) is 4 and the value ofC_(D) is 2 as an example. A value of 1 or 2 may be set as thecounter-DAI value of the UE, and the total-DAI may have a value of 1, 2,3, or 4.

(a) of FIG. 18 illustrates (counter-DAI, total-DAI) values of DCI formatreceived on MOs #0 to #6. According to the definition of the counter-DAIvalue and the total-DAI value, (counter-DAI, total-DAI) of DCI formatreceived on MO #0 is (1, 1), (counter-DAI, total-DAI) of DCI formatreceived on MO #1 is (2, 2), (counter-DAI, total-DAI) of the DCI formatreceived on MO #2 is (1, 3), (counter-DAI, total-DAI) of the DCI formatreceived on MO #3 is (2, 4), (counter-DAI, total-DAI) of the DCI formatreceived on MO #4 is (1, 1), (counter-DAI, total-DAI) of the DCI formatreceived on MO #5 is (2, 2), and (counter-DAI, total-DAI) of the DCIformat received on MO #6 is (1, 3).

As another example of the present disclosure, when the bit size of thecounter-DAI and the bit size of the total-DAI are different from eachother, a method for generating a HARQ-ACK codebook by the UE ispresented. As illustrated in (b) of FIG. 18 , the UE may not receive DCIformats of MO #4 and MO #5. In this case, the UE has received the DCIformat in which the counter-DAI value is 2 on MO #3 and the DCI formatin which the counter-DAI value is 1 on MO #6, and thus the UE may notrecognize the reception failure of the DCI format on MO #4 and MO #5.

Therefore, the UE generates only HARQ-ACK bits for DCI formats receivedon MO #0, MO #1, MO #2, MO #3, and MO #6 and includes them in theHARQ-ACK codebook.

If the UE receives 3 as the total-DAI value in the DCI format forscheduling of the PDSCH, the UE may determine that there are two moreDCI formats in addition to the five DCI formats that have beensuccessfully received. Accordingly, the UE may generate HARQ-ACK bits ofa total of seven DCI formats and include them in the HARQ-ACK codebook.

Specifically, in an embodiment of the present disclosure, the total-DAIvalue and the counter-DAI value may be used as follows. First, the valueof counter-DAI received by the UE on the last MO may be V_(temp). Asdescribed above, the counter-DAI value may have one of 1, 2, . . . ,C_(D). When the value of total-DAI received by the UE in the DCI formatfor scheduling of the PDSCH is V_(temp2), the UE may generate theHARQ-ACK codebook through the following process.

First, the UE may determine W_(temp), which is the number of DCI formatsfor scheduling of the PDSCH with V_(temp), through Equation 10 below.

W _(temp) =C _(D) *j+V _(temp)  [Equation 10]

In Equation 10, the initial value of j may be set to 0, and when thecounter-DAI value of the DCI format for scheduling of the PDSCH on thecurrent MO is smaller than the counter-DAI value of the DCI format forscheduling of the PDSCH on the previous MO, it may be incremented byone.

That is, DCI formats having the counter-DAI values of 1, 2, . . . ,C_(D)are grouped into one group, and j indicates how many grouped groups havebeen received. In (a) of FIG. 18 , j=2.

Next, the UE converts the number W_(temp) of the DCI format forscheduling of the PDSCH into V′_(temp), which is a counter-DAI valuecorresponding to N_(T-DAI), which is the bit size of the total-DAIfield. This may be performed by Equation 11 below.

V′ _(temp)=((W _(temp)−1)mod T _(D))+1  [Equation 11]

In Equation 11, V′_(temp) has one of 1, 2, . . . , T_(D), like thetotal-DAI. The UE may determine the value of j by comparing theV′_(temp) and V_(temp2). If V_(temp2)<V′_(temp), the value of j may becalculated through Equation 12 below.

$\begin{matrix}{j = {j + \frac{T_{D}}{C_{D}}}} & \left\lbrack {{Equation}12} \right\rbrack\end{matrix}$

Otherwise, j may remain as it is. Using the value of j, the UE maydetermine the size O^(ACK) of the HARQ-ACK codebook. If the UE isconfigured to receive only 1 TB per PDSCH, O^(ACK) may be calculatedthrough Equation 13 below.

O A ⁢ C ⁢ K = U D · floor ⁢ ( j · C D T D ) + V temp ⁢ 2 [ Equation ⁢ 13 ]

If the UE is configured to receive 2 TB per PDSCH, O^(ACK) may becalculated through Equation 14 below.

$\begin{matrix}{O^{ACK} = {2\left( {{{U_{D} \cdot {floor}}\left( {j \cdot \frac{C_{D}}{T_{D}}} \right)} + V_{temp2}} \right)}} & \left\lbrack {{Equation}14} \right\rbrack\end{matrix}$

In another embodiment of the present disclosure, when the bit sizes ofthe counter-DAI fields of DCI format 1_0, 1_1, or 1_2 are different fromeach other, the UE may perform the following operations.

The bit size of the counter-DAI field of the DCI format 1_0, 1_1, or 1_2received in the serving cell c in the monitoring occasion m may beN_(C-DAI,c,m) bits. In this case, the counter-DAI value may be expressedas 1, 2, . . . , 2{circumflex over ( )}N_(C-DAI,c,m). Here, the largestvalue C_(D,c,m) may be 2{circumflex over ( )}N_(C-DAI,c,m). That is,when the bit size NC-DAI,c,m of the counter-DAI field is 2 bits, thecounter-DAI value is 1 when the bit value of the counter-DAI field is‘00’, 2 when ‘01’, 3 when ‘10’, and 4 when ‘11’. Furthermore, the valueof C_(D) is 4. When N_(C-DAI,c,m) is 1 bit, the counter-DAI value is 1when the bit value of the counter-DAI field is 0, and 2 when 1.Furthermore, the value of C_(D,c,m) is 2.

If the UE receives the DCI format for scheduling of the PDSCH in theserving cell c of the monitoring occasion m, and the counter-DAI valueof the received DCI format is V_(C-DAI,c,m), the UE may determine thatC_(D,c,m)*j+V_(C-DAI,c,m) DCI formats for scheduling of the PDSCH havebeen received up to the current serving cell c of the current monitoringoccasion m where the DCI format has been received. Here, j is anon-negative integer.

In other words, when the number of DCI formats for scheduling of thePDSCH is X up to the current serving cell c of the current monitoringoccasion m where the DCI format has been received, the counter-DAI valueV_(C-DAI,c,m) of the DCI format is (X−1 mod C_(D,c,m))+1.

In the present disclosure, when the bit sizes of the counter-DAIs aredifferent from each other, a method for generating a HARQ-ACK codebookby the UE is presented. In an embodiment of the present disclosure, thecounter-DAI value is used as follows.

N_(C-DAI),min is assumed to be the minimum bit size among the bit sizesof the counter-DAI fields of the DCI formats, and the value of C_(D),inmay be 2{circumflex over ( )}(N_(C-DAI,min)). For example, when the bitsize of the counter-DAI field of one DCI format is 2 bits and the bitsize of the counter-DAI field of another DCI format is 1 bit, the valueof N_(C-DAI),min is 1 and the value of C_(D,min) is 2.

When the value of counter-DAI received in serving cell c of themonitoring occasion m is V_(C-DAI,c,m), the value of counter-DAI mayhave one of is 1, 2, . . . , C_(D,c,m), as described above. First, theUE may determine the number S_(c,m) of the DCI format for scheduling ofthe PDSCH with V_(C-DAI,c,m) based on Equation 15 below.

$\begin{matrix}{S_{c,m} = {{{floor}\left( {j*\frac{C_{D,\min}}{C_{D,c,m}}} \right)*C_{D,c,m}} + V_{{C - {DAI}},c,m}}} & \left\lbrack {{Equation}15} \right\rbrack\end{matrix}$

In Equation 15, the part of floor(j*C_(D,min)/C_(D,c,m))*C_(D,c,m) is apart for letting the number S_(c,m) of DCI formats for scheduling of thePDSCH satisfy (S_(c,m)−1 mod C_(D,c,m))+1=V_(C-DAI,c,m).

That is, the value of j may be adjusted through scaling and/or flooringso that the value of S_(c,m)−V_(c-DAI,c,m) is a multiple of c, inEquation 15.

The UE compares the number S_(c,m) of DCI formats obtained based on thecounter-DAI values received in the serving cell c in the currentmonitoring occasion m with the number W_(temp) of DCI formats obtainedimmediately before. If S_(c,m)≤W_(temp) is satisfied, the value of j maybe incremented until S_(c,m)>W_(temp). In this case, the value of j maybe incremented by one. If S_(c,m)>W_(temp), j may remain as it is.

j is a parameter indicating how many C_(D,min) DCI formats have beenreceived.

When this is expressed in a pseudo-code, it is shown in Table 12 below.

TABLE 12 Denote by N_(C−DAI,c,m) the number of bits for the counter DAIin a DCI format detected in monitoring occasion m in a serving cell cand set C_(D,c,m)=2{circumflex over ( )}N_(C−DAI,c,m). Denote byN_(C−DAI,min) the minimum number of bits for the counter DAI in a DCIformats and set C_(D,min)=2{circumflex over ( )}N_(C−DAI,c,m). Denote byN_(T−DAI,m) the number of bits for the total DAI in a DCI formatdetected in monitoring occasion m and set T_(D,m)=2{circumflex over( )}N_(T−DAI,m). Denote by N_(UL−DAI) the number of bits for the UL DAIin a DCI format scheduling a PUSCH transmission and setU_(D)=2{circumflex over ( )}N_(UL−DAI). If the UE transmits HARQ-ACKinformation in a PUCCH in slot n and for any PUCCH format, the UEdetermines the ${\overset{\sim}{o}}_{0}^{ACK},{\overset{\sim}{o}}_{1}^{ACK},\ldots,{\overset{\sim}{o}}_{O^{ACK} - 1}^{ACK},$for a total number of OACK HARQ-ACK information bits, according to thefollowing pseudo-code:  Set m=0 - PDCCH with DCI format scheduling PDSCHreception or SPS PDSCH release monitoring   occasion index: lower indexcorresponds to earlier PDCCH monitoring occasion  Set j=0  SetV_(temp)=0, W_(temp)=0  Set V_(temp2)=0  Set V_(s) as an empty set  SetN_(cells) to the number of serving cells configured by higher layers forthe UE  Set M to the number of PDCCH monitoring occasion(s)  While m<M  Set c=0 - serving cell index: lower indexes correspond to lower RRCindexes of corresponding cell   while c<N_(cells)    if PDCCH monitoringoccasion m is before an active DL BWP change on serving cell c or an   active UL BWP change on the PCell and an active DL BWP change is nottriggered in PDCCH    monitoring occasion m     c=c+1;    else     ifthere is a PDSCH on serving cell c associated with PDCCH in PDCCHmonitoring occasion     m, or there is a PDCCH indicating SPS PDSCHrelease on serving cell c     $S_{c,m} = {{{{floor}\left( {j*\frac{C_{D,\min}}{C_{D,c,m}}} \right)}*C_{D,c,m}} + V_{{C - {DAI}},c,m}}$    while S_(c,m) ≤ W_(temp)      j = j + 1      $S_{c,m} = {{{{floor}\left( {j*\frac{C_{D,\min}}{C_{D,c,m}}} \right)}*C_{D,c,m}} + V_{{C - {DAI}},c,m}}$    end while     W_(temp) = S_(c,m)     if V_(T−DAI,m)is empty     V_(temp2) = V_(C−DAI,c,m)     else      V_(temp2) = V_(T−DAI,m)    end if     if harq-ACK-SpatialBundlingPUCCH is not provided and theUE is configured by     maxNrofCodeWordsScheduledByDCI with reception oftwo transport blocks for at least     one configured DL BWP of at leastone serving cell,      õ_(2(W) _(temp) ⁻¹⁾ ^(ACK) = HARQ-ACK informationbit corresponding to the first transport block       of this cell     õ_(2(W) _(temp) ⁻¹⁾⁺¹ ^(ACK) = HARQ-ACK information bitcorresponding to the second transport       block of this cell V_(s) =V_(s) ∪ {2(W_(temp) − 1), 2(W_(temp) − 1) + 1}     elseifharq-ACK-SpatialBundlingPUCCH is provided to the UE and m is amonitoring     occasion for PDCCH with a DCI format that supports PDSCHreception with two transport     blocks and the UE is configured bymaxNrofCodeWordsScheduledByDCI with reception     of two transportblocks in at least one configured DL BWP of a serving cell,      õ_(W)_(temp) ⁻¹ ^(ACK)= binary AND operation of the HARQ-ACK information bitscorresponding       to the first and second transport blocks of thiscell V_(s) = V_(s) ∪ {W_(temp) − 1}     else      õ_(W) _(temp) ⁻¹^(ACK) = HARQ-ACK information bit of this cell V_(s) = V_(s) ∪ {W_(temp)− 1}     end if    end if    c=c+1   end if  end while   m=m+1  endwhile  if V_(temp2) < ((W_(temp) − 1) mod T_(D) ) + 1 or V_(temp) = 0   $j = {j + \frac{T_{D}}{C_{D,\min}}}$  end if  ifharq-ACK-SpatialBundlingPUCCH is not provided to the UE and the UE isconfigured by  maxNrofCodeWordsScheduledByDCI with reception of twotransport blocks for at least one configured  DL BWP of a serving cell,  $O^{ACK} = {2 \cdot \left( {{T_{D} \cdot {{floor}\left( {j \cdot \frac{C_{D,\min}}{U_{D}}} \right)}} + V_{{temp}2}} \right)}$ else   $O^{ACK} = {{T_{D} \cdot {{floor}\left( {j \cdot \frac{C_{D,\min}}{U_{D}}} \right)}} + V_{{temp}2}}$ end if õ_(i) ^(ACK) = NACK for any i ∈{0,1,..., O^(ACK) − 1}\V_(s)

In Table 12, when the HARQ-ACK codebook is multiplexed with the PUSCH,T_(D)=U_(D), and V_(temp2) after the while statement may be set to thevalue of UL DAI.

DCI format 1_2 may not include counter-DAI (this includes beingconfigured with 0 bits). In this case, the UE may be ambiguous about amethod for determining the dynamic HARQ-ACK codebook. That is, indesigning the dynamic HARQ-ACK codebook (type-2 HARQ-ACK codebook), thebase station may be configured to omit some of the DCI field in order toincrease the PDCCH reception success probability of the UE. That is, thebase station may omit some of the DCI field or set the field size to 0bits.

For example, the base station may omit the counter-DAI field from amongDCI fields to be transmitted to the UE, or set the size of the field to0 bits.

As described above, in the dynamic HARQ-ACK codebook, the counter-DAIfield may be used not only to determine the position of the HARQ-ACK bitin the HARQ-ACK codebook, but also to determine the size of the HARQ-ACKcodebook.

In order for the UE to transmit HARQ-ACK bits for notifying the basestation of ACK/NACK (or DTX) for a plurality of PDSCHs with the HARQ-ACKcodebook, the values of the counter-DAI fields of DCI need to bearranged in ascending order, but when the counter-DAI field is omitted,values of the counter-DAI fields may not be sorted in ascending orderthrough explicit values, and thus a method for determining the order ofHARQ-ACK bits in the HARQ-ACK codebook is required.

Therefore, a method for generating a HARQ-ACK codebook according to apredetermined criterion even when some fields of DCI are omitted will bedescribed.

FIG. 20(a) and FIG. 20(b) illustrate an example of a method fortransmitting a HARQ-ACK for a PDSCH according to a reception order of aPDCCH according to an embodiment of the present disclosure.

Referring to FIG. 20(a) and FIG. 20(b), when some of the DAI field isomitted or the size is set to 0 bits, the UE may generate the HARQ-ACKcodebook according to the order in which the PDCCHs for schedulingPDSCHs are received, not the counter-DAI values.

In the first embodiment of the present disclosure, the UE may determinethe order of HARQ-ACK bits for the PDSCHs in the HARQ-ACK codebook basedon time information at which the PDCCH for scheduling of the PDSCH isreceived. That is, the UE may determine the order of HARQ-ACK bitsincluded in the HARQ-ACK codebook according to the order in which thePDCCHs are received, regardless of the value of the counter-DAI in thePDCCH transmitted to schedule the PDSCH.

For example, when a starting symbol of a CORESET including the PDCCH forscheduling the first PDSCH or its search space is positioned before astarting symbol of a CORESET including the PDCCH for scheduling thesecond PDSCH or its search space as illustrated in (a) of FIG. 20 , inthe HARQ-ACK codebook, B(1), which is the HARQ-ACK bit of the firstPDSCH may be disposed at a position before B(0), which is the HARQ-ACKbit of the second PDSCH, as illustrated in (b) of FIG. 20 . If thestarting symbols of the CORESETs or search spaces are the same as eachother, the HARQ-ACK bit of the PDSCH scheduled by the PDCCH for whichthe last symbol of the CORESET or its search space precedes may bedisposed at a preceding position.

FIG. 21(a) and FIG. 21(b) illustrate an example of a method fortransmitting a HARQ-ACK for a PDSCH according to time information abouta PDSCH according to an embodiment of the present disclosure.

Referring to FIG. 21(a) and FIG. 21(b), when some of the DAI field isomitted or the size is set to 0 bits, the UE may generate the HARQ-ACKcodebook according to time information about the PDSCH included in thePDCCH for scheduling the PDSCH, not the counter-DAI values.

In the second embodiment of the present disclosure, the UE may determinethe order of the HARQ-ACK bits of PDSCHs constituting the HARQ-ACKcodebook according to the time information about the PDSCHs.Specifically, when a starting symbol of the first PDSCH is positionedbefore a starting symbol of the second PDSCH, in the HARQ-ACK codebook,the position of the HARQ-ACK bit for the first PDSCH may precede theposition of the HARQ-ACK for the second PDSCH.

For example, as illustrated in (a) of FIG. 21 , the starting symbol ofthe second PDSCH may be positioned before the starting symbol of thefirst PDSCH, based on time information included in the PDCCH forscheduling of the first PDSCH and the time information included in thePDCCH for scheduling the second PDSCH. In this case, as illustrated in(b) of FIG. 21 , in the UE transmitting the HARQ-ACK for the first PDSCHand the HARQ-ACK for the second PDSCH through the PUCCH, B(1), which isthe HARQ-ACK bit for the second PDSCH, may be positioned before B(0),which is the HARQ-ACK bit for the first PDSCH.

FIG. 22(a) and FIG. 22(b) illustrate an example of a method oftransmitting a HARQ-ACK for a PDSCH according to a HARQ process ID (orHARQ process number) of a PDCCH for scheduling the PDSCH according to anembodiment of the present disclosure.

Referring to FIG. 22(a) and FIG. 22(b), when some of the DAI field isomitted or the size is set to 0 bits, the UE may generate the HARQ-ACKcodebook according to the HARQ process ID (or HARQ process number)included in the PDCCH for scheduling the PDSCH, not the counter-DAIvalues.

In the third embodiment of the present disclosure, the UE may determinethe order of the HARQ-ACK bits in the HARQ-ACK codebook according to thevalue of the HARQ process ID (or HARQ process number) of the PDCCH forscheduling the PDSCH.

Specifically, when the HARQ process ID of the first PDSCH in the PDCCHfor scheduling the first PDSCH is A and the HARQ process ID of thesecond PDSCH in the PDCCH for scheduling the second PDSCH is B, in theHARQ-ACK codebook, the HARQ-ACK bit of the PDSCH with a smaller valueamong A and B values may be disposed before the HARQ-ACK bit of thePDSCH with a larger value.

That is, the position of the HARQ-ACK bit may be determined according tothe ascending order of the HARQ process IDs. Here, the UE may assumethat HARQ process IDs of HARQ-ACKs transmitted with one HARQ-ACKcodebook have values different from each other. Therefore, it is notexpected that one HARQ-ACK codebook having the HARQ-ACK bit of the PDSCHhaving the same HARQ process ID is generated.

For example, when the number of bits of the counter-DAI field includedin at least one of the PDCCH for scheduling the first PDSCH and thePDCCH for scheduling the second PDSCH is different or omitted, or thesize is set to 0 bits, the UE may generate the HARQ-ACK codebook basedon the HARQ-ACK process ID included in the PDCCH for scheduling eachPDSCH and transmit it to the base station through UCI.

In this case, as illustrated in (a) of FIG. 22 , the value of theHARQ-ACK process ID or HARQ-ACK process number of the PDCCH forscheduling the second PDSCH may be ‘0’, and the value of the HARQ-ACKprocess ID or HARQ-ACK process number of the PDCCH for scheduling thefirst PDSCH may be ‘1’. In this case, as illustrated in (b) of FIG. 15 ,based on the ascending order of the HARQ-ACK process IDs or HARQ-ACKprocess numbers, B(0), which is the HARQ-ACK bit for the second PDSCHwith a lower HARQ-ACK process ID or HARQ-ACK process number, may bepositioned before B(1), which is the HARQ-ACK bit for the first PDSCH.

In a fourth embodiment of the present disclosure, the UE may determinethe order of the HARQ-ACK bits of the PDSCH in the HARQ-ACK codebook byusing cell information on the received PDCCH for scheduling each PDSCH.Cell information may mean an index (or ID) of a cell. The UE may beconfigured to monitor PDCCHs in a plurality of cells. In this case, theUE may receive different PDCCHs in different cells. The UE may arrangeHARQ-ACK bits of PDSCHs received in different cells in the HARQ-ACKcodebook according to the ascending order of the indexes of the cellsthat have received the PDCCHs for scheduling the PDSCHs.

In a fifth embodiment of the present disclosure, the UE may determinethe order of the HARQ-ACK bits of the PDSCH by using information aboutthe CORESET (or search space) that has received the PDCCH for schedulingthe PDSCH to generate the HARQ-ACK codebook. Here, the information aboutCORESET (or search space) may be an index (or ID) of CORESET (or searchspace).

The UE may be configured to monitor the PDCCH in a plurality of CORESETs(or search spaces). In this case, the UE may receive different PDCCHs indifferent CORESETs (or search spaces). In this case, the UE may arrangethe order of HARQ-ACK bits of PDSCHs received in different CORESETs (orsearch spaces) according to the ascending order of the indexes of theCORESETs (or search spaces) that have received the PDCCHs for schedulingthe PDSCHs to generate the HARQ-ACK codebook.

In a sixth embodiment of the present disclosure, the UE may determinethe order of the HARQ-ACK bits of the PDSCH in the HARQ-ACK codebook byusing frequency domain information about the PDCCH for scheduling thePDSCH. Here, the frequency domain information may be the lowest PRBindex among the PRBs to which the PDCCH is allocated. Here, index meanscommon PRB index, and this index indicates how far away from Point A inthe frequency domain. Point A means the reference frequency of the UE inan initial access process, and specifically, Point A is as follows.

-   -   offsetToPointA indicates a frequency offset between Point A and        the lowest subcarrier of the lowest resource block. The lowest        resource block has a subcarrier spacing provided by the higher        layer parameter subCarrierSpacingCommon and overlaps with the        SS/PBCH block used by the UE for initial cell selection.        offsetToPointA is expressed in units of resource blocks assuming        a 15 kHz subcarrier spacing for FR1 and a 60 kHz subcarrier        spacing for FR2.    -   absoluteFrequencyPointA indicating the frequency position of        Point A is expressed as an absolute radio frequency channel        number (ARFCN) for all other cases.

The UE may be configured to monitor a plurality of PDCCHs, and mayreceive different PDCCHs in different frequency domains. In this case,the UE may arrange HARQ-ACK bits of PDSCHs received in differentfrequency domains in the HARQ-ACK codebook according to the ascendingorder of the lowest PRB indexes of the PDCCHs for scheduling the PDSCHs.In this method, when a plurality of PDCCHs are received by the UE in oneCORESET (or search space) in the fifth embodiment, the order of HARQ-ACKbits in the HARQ-ACK codebook may be determined.

The first to sixth embodiments may be used in combination with eachother, through which the UE may determine the order of HARQ-ACK bits forrespective PDSCHs in the HARQ-ACK codebook. For example, the firstembodiment and the third embodiment may be combined. With thiscombination, the order of the HARQ-ACK bits in the HARQ-ACK codebook maybe first determined according to the time domain information about thePDCCH, and when the order may not be determined by the time domaininformation, the order may be determined according to the HARQ processID according to the third embodiment. Alternatively, the first, fourth,fifth, and sixth embodiments may be combined. With this combination, theorder of the HARQ-ACK bits in the HARQ-ACK codebook may be firstdetermined according to the time domain information about the PDCCH.Then, when the order may not be determined by the time domaininformation according to each embodiment, the order is determinedaccording to the cell information, and when the order may not bedetermined by the cell information, the order may be determinedaccording to the information about the CORESET (or search space). Inaddition, when the order may not be determined with the informationabout the CORESET (or search space), the order may be determinedaccording to the frequency domain allocation information about thePDCCH.

In addition, in another embodiment of the present disclosure, whenPDSCHs are each scheduled through a plurality of PDCCHs and the numberof bits of the counter-DAI fields included in the plurality of PDCCHsare different from each other, the UE may individually generate each ofthe HARQ-ACK codebooks according to the number of bits of thecounter-DAI without multiplexing according to the number of bits.

For example, when the number of bits of the counter-DAI field is 2 bitsor 1 bit, the UE may individually generate each of the HARQ-ACK codebookfor PDSCHs scheduled by the PDCCH including a counter-DAI with a bitnumber of 2 bits, and/or the HARQ-ACK codebook for PDSCHs scheduled bythe PDCCH including the counter-DAI with a bit number of 1 bit andtransmit them to the base station.

That is, for the UE, one HARQ-ACK codebook may include only HARQ-ACKs ofPDSCHs scheduled with DCI formats with the same number of bits of thecounter-DAI.

Through the first to sixth embodiments described above, the UE maydetermine the position of the bits of the HARQ-ACK in the HARQ-ACKcodebook without the counter-DAI field. However, in generating aHARQ-ACK codebook including HARQ-ACK bits for each PDSCH, a problem mayoccur when the UE determines the size of the HARQ-ACK codebook.

For example, when the UE does not receive one of the PDCCHs, the UE maydetermine the size of the HARQ-ACK codebook differently due to the PDCCHthat has not been received, and thus a method for solving this isrequired.

In this case, the UE may always assume that the remainder is Y when thesize of the dynamic HARQ-ACK codebook is divided by X. It is desirablethat X=4 and Y=1. That is, the size of the dynamic HARQ-ACK codebook maybe determined as one of 1, 5, 9, bits. When the UE receives the PDCCHfor scheduling Z PDSCHs, the UE may determine the smallest value amongsizes greater than or equal to Z as the size of the HARQ-ACK codebook.For example, if Z=3, 5 may be determined as the size of the HARQ-ACKcodebook.

The counter-DAI field may or may not be included in the DCI of the PDCCHcorresponding to the HARQ-ACK of one HARQ-ACK codebook. In this case, inthe HARQ-ACK codebook, the UE determines the positions of the HARQ-ACKof the PDSCH scheduled by the DCI including the counter-DAI field andthe HARQ-ACK of the PDSCH scheduled by the DCI without the counter-DAI

FIELD

In an embodiment of the present disclosure, in this case, the UE mayindividually generate each of the HARQ-ACK codebooks according towhether the DCI includes the counter-DAI field.

Specifically, the UE generates a first sub-HARQ-ACK codebook bycollecting only HARQ-ACKs of PDSCHs scheduled by DCI including thecounter-DAI field. In this case, the position of the HARQ-ACK in thefirst sub-HARQ-ACK codebook is determined by using the value of thecounter-DAI field (that is, the position is determined according to theascending order of the counter-DAIs). In this case, when the numbers ofbits of the counter-DAI fields are different from each other, the methodof first to sixth embodiments described above and a combination thereofmay be used.

In addition, the UE generates a second sub-HARQ-ACK codebook bycollecting only HARQ-ACKs of PDSCHs scheduled by DCI, in which thecounter-DAI field is omitted or is set to a 0-bit value. In this case,the position of the HARQ-ACK in the second sub-HARQ-ACK codebook may bedetermined according to the first to sixth embodiments described aboveand a combination thereof. The UE continuously may combine the firstsub-HARQ-ACK codebook and the second sub-HARQ-ACK codebook (that is,such that the first bit of the second sub-HARQ-ACK codebook comes afterthe last bit of the first sub-HARQ-ACK codebook) to generate a HARQ-ACKcodebook. In this method, the UE needs to generate two sub-HARQ-ACKcodebooks in different ways, and UE complexity may increase,accordingly.

In another embodiment of the present disclosure, in the above situation,the UE may ignore the counter-DAI field included in the DCI. That is, byconsidering all DCI as DCI without the counter-DAI field, the positionsof the HARQ-ACK bits in the HARQ-ACK codebook may be determined by usingthe first to sixth embodiments and a combination thereof.

In another embodiment of the present disclosure, a UE configured with asemi-static HARQ-ACK codebook may determine HARQ-ACK bits for one PDSCH.

Specifically, the UE configured with the semi-static HARQ-ACK codebookneeds to transmit the HARQ-ACK codebook including a predetermined numberof HARQ-ACK bits to the PUCCH. In this case, the predetermined numbermay be determined regardless of which PDSCH is actually scheduled by theUE, and may be derived from information set as a higher layer.

The information set as the higher layer may include at least CBGconfiguration information of a cell, and the UE may receive CBGconfiguration information for each cell. The CGB configurationinformation may be used to configure the maximum number of CBGs that onePDSCH (or TB) may include, and may be expressed as N_(MAX). In thesemi-static HARQ-ACK codebook, when HARQ-ACK bits of PDSCHs areincluded, it needs to be determined how many bits of HARQ-ACK one PDSCHcorresponds to. In general, when CBG transmission is not configured, thePDSCH may correspond to 1-bit HARQ-ACK (2 bits when 2 TB transmission isconfigured), and when CBG transmission is configured, the PDSCH maycorrespond to N_(MAX) bits HARQ-ACK.

When the semi-static HARQ-ACK is configured for the UE, the number ofHARQ-ACK bits determined above needs to be included in the PUCCH. Evenif CBG-based transmission is configured, in a specific situation, the UEmay transmit only 1-bit HARQ-ACK for the PDSCH by including it in thePUCCH.

For example, when CBG-based transmission is configured, one downlinkcell (or carrier) is configured in the UE while satisfying at least oneof the following cases, and when there is one monitoring occasion forreceiving the PDCCH, the UE may generate only 1 bit of HARQ-ACK of theSPS PDSCH or SPS PDSCH release DCI or PDSCH.

-   -   When the UE needs to transmit HARQ-ACK for one SPS PDSCH    -   When one SPS PDSCH release DCI is received    -   When HARQ-ACK of PDSCH scheduled in DCI format 1_0 or DCI format        1_2 is transmitted

That is, even if CBG-based transmission is configured, the UE maygenerate only HARQ-ACK of 1 bit per PDSCH.

In contrast, when CBG-based transmission is configured, and when atleast one of the following conditions is satisfied, and two or moredownlink cells (or carriers) are configured in the UE or there are twoor more monitoring occasions for receiving the PDCCH, the UE maygenerate N_(MAX) bits by repeating 1 bit of HARQ-ACK (TB-level HARQ-ACK)of SPS PDSCH or SPS PDSCH release DCI or PDSCH N_(MAX) times.

-   -   When HARQ-ACK for one SPS PDSCH is transmitted    -   When one SPS PDSCH release DCI is received    -   When HARQ-ACK of PDSCH scheduled in DCI format 1_0 or DCI format        1_2 is transmitted

That is, in accordance with CBG-based transmission, the UE may generateonly HARQ-ACK of N_(M)Ax bits per PDSCH.

In the above operation, DCI format 1_2 is a DCI format that may set thesize of each field for high reliability and low latency. This DCI format1_2 does not support CBG-based operation. That is, the PDSCH scheduledin DCI format 1_2 always corresponds to 1 bit of TB-level HARQ-ACK. Thisis similar to DCI format 1_0. Therefore, DCI format 12 may be handled inthe same way as DCI format 1_0.

FIG. 23 is a flowchart illustrating an example of an operation of a UEfor transmitting a HARQ-ACK based on downlink information having adifferent format according to an embodiment of the present disclosure.

Referring to FIG. 23 , the UE may generate a HARQ-ACK codebook includingHARQ-ACK bits for a plurality of PDSCHs scheduled by DCI on a pluralityof PDCCHs transmitted from the base station. In this case, when theformat of the DCI is different and the number of bits of the DAI fieldincluded in each piece of DCI is different, the UE may interpret thevalue of the DAI field under a certain condition to generate theHARQ-ACK codebook.

First, the UE receives a first PDCCH for scheduling of a first downlinkphysical shared channel (PDSCH) (S23010). In this case, the UE mayreceive setting information including information for receiving thePDCCH before receiving the first PDCCH.

The first PDCCH may include a first counter downlink assignmentindicator(DAI) indicating the number of PDSCHs scheduled until a timepoint at which the first PDCCH is monitored, and a first total DAIindicating the number of all PDSCHs scheduled in a serving cell.

Then, the UE receives a second PDCCH for scheduling of a second PDSCHincluding a second counter DAI and a second total DAI (S23020).

Then, the UE receives the first PDSCH based on the first PDCCH (S23030)and receives the second PDSCH based on the second PDCCH (S23040).

After receiving the first PDSCH and the second PDSCH, the UE generatesHARQ-ACK bits for each of the first and second PDSCHs, and generates theHARQ-ACK codebook by using the generated HARQ-ACK bits.

Then, the UE transmits uplink control information (UCI) including theHARQ-ACK codebook to the base station (S23050).

The value of the second counter DAI may be recognized based on thenumber of bits of the first counter DAI when the number of bits of thefirst counter DAI is different from the number of bits of the secondcounter DAI. That is, when the number of bits of the first counter DAIis different from the number of bits of the second counter DAI, the UEmay generate a HARQ-ACK codebook including HARQ-ACK bits through themethods of Proposals 1 to 3 described above.

For example, when the number of the bits of the first counter DAI issmaller than the number of the bits of the second counter DAI, a valueindicated by the second counter DAI may be recognized based on at leastone of bits with a number equal to the number of bits of the firstcounter DAI among bits of the second counter DAI.

Alternatively, when the number of bits of the first counter DAI isgreater than the number of bits of the second counter DAI, the valueindicated by the second counter DAI may be interpreted by extending thenumber of bits of the second counter DAI to the same number of bits asthe number of bits of the first counter DAI.

In this case, when there are a plurality of candidate values of thesecond counter DAI, the value of the second counter DAI may beinterpreted as a value with the smallest difference from a valueindicated by the first counter DAI among the plurality of candidatevalues.

FIG. 24 is a flowchart illustrating an example of an operation of a basestation for receiving a HARQ-ACK based on downlink information having adifferent format according to an embodiment of the present disclosure.

Referring to FIG. 24 , the base station may schedule the PDSCH to the UEthrough a plurality of PDCCHs having a different format. In this case,when the number of bits of the DAI field included in DCI of a differentformat on the PDCCH is different, the base station may receive aHARQ-ACK codebook for PDSCHs scheduled by DCI of the different formatfrom the UE.

First, the base station transmits a first PDCCH for scheduling of afirst downlink physical shared channel (PDSCH) to the UE (S24010). Inthis case, the base station may transmit setting information includinginformation for receiving the PDCCH before transmitting the first PDCCH.

The first PDCCH may include a first counter downlink assignmentindicator(DAI) indicating the number of PDSCHs scheduled until a timepoint at which the first PDCCH is monitored, and a first total DAIindicating the number of all PDSCHs scheduled in a serving cell.

Then, the base station transmits a second PDCCH for scheduling of asecond PDSCH including a second counter DAI and a second total DAI(S24020).

Then, the base station transmits the first PDSCH based on the firstPDCCH (S24030) and transmits the second PDSCH based on the second PDCCH(S24040).

The base station receives a HARQ-ACK codebook including HARQ-ACK bitsfor each of the first PDSCH and the second PDSCH generated by the UEthrough uplink control information (UCI) from the UE (S24050).

The value of the second counter DAI may be recognized based on thenumber of bits of the first counter DAI when the number of bits of thefirst counter DAI is different from the number of bits of the secondcounter DAI. That is, when the number of bits of the first counter DAIis different from the number of bits of the second counter DAI, the UEmay generate a HARQ-ACK codebook including HARQ-ACK bits through themethods of Proposals 1 to 3 described above.

For example, when the number of the bits of the first counter DAI issmaller than the number of the bits of the second counter DAI, a valueindicated by the second counter DAI may be recognized based on at leastone of bits with a number equal to the number of bits of the firstcounter DAI among bits of the second counter DAI.

Alternatively, when the number of bits of the first counter DAI isgreater than the number of bits of the second counter DAI, the valueindicated by the second counter DAI may be interpreted by extending thenumber of bits of the second counter DAI to the same number of bits asthe number of bits of the first counter DAI.

In this case, when there are a plurality of candidate values of thesecond counter DAI, the second counter DAI value may be interpreted as avalue with the smallest difference from a value indicated by the firstcounter DAI among the plurality of candidate values.

The above description of the present disclosure is for illustration, andthose of ordinary skill in the art to which the present disclosurepertains could understand that it may be easily modified into otherspecific forms without changing the technical spirit or essentialfeatures of the present disclosure. Therefore, it is to be appreciatedthat the embodiments described above are intended to be illustrative inall respects and not restrictive. For example, each component describedas a single type may be implemented in a distributed manner, andsimilarly, components described to be distributed may also beimplemented in a combined form.

The scope of the present disclosure is represented by the claims to bedescribed below rather than the above detailed description, and it is tobe interpreted that the meaning and scope of the claims and all changesor modifications derived from the equivalents thereof come within thescope of the present disclosure.

1-22. (canceled)
 23. A user equipment for use in a wireless communication system, the user equipment comprising: a communication module; and a processor for controlling the communication module, wherein the processor is configured to, receive a plurality of first downlink control information (DCI) formats for downlink scheduling, wherein each of the plurality of the first DCI formats includes an Nc-bit counter downlink assignment index (c-DAI), and Nc is one of 1 and 2; receive a second DCI format for scheduling a physical uplink shared channel (PUSCH), wherein the second DCI format includes 2-bit uplink DAI (UL-DAI); and transmit a hybrid automatic repeat request (HARQ)-acknowledge (ACK) codebook for the downlink scheduling via the PUSCH, wherein a bit size of the HARQ-ACK codebook is associated with O having: i) a first value: 4*floor(j*C/4)+V, or ii) a second value, which is larger than the first value by 4, where j is a counter value for a case that a value of a Nc-bit c-DAI is less than or equal to a value of a previous Nc-bit c-DAI within a plurality of received Nc-bit c-DAIs, C is 2^(Nc), V is a value of the 2-bit UL-DAI, and in a range of 1 to 4, and floor is a flooring function.
 24. The user equipment of claim 23, wherein Nc is
 1. 25. The user equipment of claim 23, wherein the bit size of the HARQ-ACK codebook is determined as either O or P*O, and P is a positive integer.
 26. The user equipment of claim 23, wherein O has the second value only when V is less than V_(temp), and wherein, when Nc is 1, V_(temp) is determined as a 2-bit c-DAI value converted from a value of a last one of the plurality of received Nc-bit c-DAIs, so that the converted 2-bit c-DAI value corresponds to a number of the downlink scheduling determined based on the plurality of received Nc-bit c-DAIs.
 27. The user equipment of claim 26, wherein a value of the last one of the plurality of received Nc-bit c-DAIs, and the converted 2-bit c-DAI value satisfy a relation including the following table: j 0 0 1 1 2 2 3 . . . X 1 2 1 2 1 2 1 . . . Y 1 2 3 4 1 2 3 . . .

where X represents the value of the last one of the plurality of received Nc-bit c-DAIs, and Y represents the converted 2-bit c-DAI value.
 28. The user equipment of claim 23, wherein the Nc-bit c-DAI is associated with a bit position of a corresponding HARQ-ACK information in the HARQ-ACK codebook.
 29. The user equipment of claim 23, wherein the Nc-bit c-DAI is related to a counter number of a corresponding downlink scheduling, and the 2-bit UL DAI is related to a total number of the downlink scheduling.
 30. The user equipment of claim 23, wherein the wireless communication system includes 3^(rd) generation partnership project (3GPP)-based wireless communication system.
 31. A method performed by a user equipment in a wireless communication system, the method comprising: receiving a plurality of first downlink control information (DCI) formats for downlink scheduling, wherein each of the plurality of the first DCI formats includes an Nc-bit counter downlink assignment index (c-DAI), and Nc is one of 1 and 2; receiving a second DCI format for scheduling physical uplink shared channel (PUSCH), wherein the second DCI format includes 2-bit uplink DAI (UL-DAI); and transmitting a hybrid automatic repeat request (HARQ)-acknowledge (ACK) codebook for the downlink scheduling via the PUSCH, wherein a bit size of the HARQ-ACK codebook is associated with O having: i) a first value: 4*floor(j*C/4)+V, or ii) a second value, which is larger than the first value by 4, where j is a counter value for a case that a value of a Nc-bit c-DAI is less than or equal to a value of a previous Nc-bit c-DAI within a plurality of received Nc-bit c-DAIs, C is 2^(Nc), V is a value of the 2-bit UL-DAI, and in a range of 1 to 4, and floor is a flooring function.
 32. The method of claim 31, wherein Nc is
 1. 33. The method of claim 31, wherein the bit size of the HARQ-ACK codebook is determined as either O or P*O, and P is a positive integer.
 34. The method of claim 31, wherein O has the second value only when V is less than V_(temp), and wherein, when Nc is 1, V_(temp) is determined as a 2-bit c-DAI value converted from a value of a last one of the plurality of received Nc-bit c-DAIs, so that the converted 2-bit c-DAI value corresponds to a number of the downlink scheduling determined based on the plurality of received Nc-bit c-DAIs.
 35. The method of claim 34, wherein a value of the last one of the plurality of received Nc-bit c-DAIs, and the converted 2-bit c-DAI value satisfy a relation including the following table: j 0 0 1 1 2 2 3 . . . X 1 2 1 2 1 2 1 . . . Y 1 2 3 4 1 2 3 . . .

where X represents the value of the last one of the plurality of received Nc-bit c-DAIs, and Y represents the converted 2-bit c-DAI value.
 36. The method of claim 31, wherein the Nc-bit c-DAI is associated with a bit position of a corresponding HARQ-ACK information in the HARQ-ACK codebook.
 37. The method of claim 31, wherein the Nc-bit c-DAI is related to a counter number of a corresponding downlink scheduling, and the 2-bit UL DAI is related to a total number of the downlink scheduling.
 38. The method of claim 31, wherein the wireless communication system includes 3^(rd) generation partnership project (3GPP)-based wireless communication system. 